Control of a host station through movement of a moving device

ABSTRACT

A method for controlling a host device for at least one moving device including the following steps: determining a current position of the at least one moving device relative to an interaction surface of the host station using at least one electrical signal induced by at least one inductive magnetic field in at least one electric circuit of the host device associated with the interaction surface; recording the current position in a position history; using the history to compare a change of the position of the at least one device with at least one reference change diagram, the reference change diagram being associated with at least one reference movement; and activating a command of the host station on the basis of the reference movement, if the change corresponds to the reference movement.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention concerns the interfaces between a user and acomputer system, in particular in the field of games, and moreparticularly a method and devices for interfacing a plurality of mobiledevices with a computer system.

In numerous situations, it may be necessary, for a computer system, todetect the position and/or the orientation of mobile entities to enablethe latter to react accordingly. Thus, for example, in a game of chessenabling a user to play against a virtual user simulated by the computersystem, the application implemented on the computer system must know theposition of all the pieces of the chess board, in particular those movedby the user, to compute its move.

Description of the Related Art

There are solutions for detecting the position and/or the orientation ofreal objects on a game board making it possible to use those objects asan interface for a computer system.

Thus, for example, resistive type touch screens may be used as a boardgame in order to detect the position of an object such as a stylus whensufficient pressure is applied. However, this type of screen in generalonly supports a single contact and requires constant pressure by theuser to know the position. In other words, it is not possible to detectthe position of the stylus if the pressure applied by the latter isrelaxed.

It is also possible to use capacitive type touch screens, based on theprinciple of a leakage of current through a conductive body. However,only objects that are conductive and linked to a ground enable thedetection of their position. Thus, for example, the positions of objectsof plastic or wood cannot be determined using such screens.

Moreover, in general terms, the solutions based on touch screens ortouch film, only support a limited number of simultaneous or almostsimultaneous contacts and do not enable the determination of a highnumber of objects.

Other solutions implement technologies based on infrared, in particularin the form of tables. Thus, for example, the products known under thenames Surface (Surface is a trademark of Microsoft), mTouch (mTouch is atrademark of Merel Technologies) and Entertaible (Entertaible is atrademark of Philips) use infrared cameras disposed within the thicknessof the table. However, the required thickness of these tables makes thembulky and of low mobility and gives them a certain rigidity.Furthermore, their price does not really allow for family use.

Lastly, these solutions do not enable detection of the altitude,relative to a predetermined reference, of the mobile entities of whichthe movements and/or orientations are detected.

In document WO 2012/028827 a method has been provided to enable acomputer system to simply and efficiently determine the position of ahigh number of mobile devices which may be used to interact with thatcomputer system. A method of assisting location of mobile devices hasalso been described in French patent application FR 1255334.

BRIEF SUMMARY OF THE INVENTION

The present invention lies within this context.

The inventors have identified the possibility of using the detection ofthe position of one or more mobile devices relative to the host stationto create a new type of interface with the computer system of the hoststation.

A first aspect of the invention concerns a method of controlling a hostdevice for at least one mobile device comprising the following steps of:

-   -   determining a current position of said at least one mobile        device relative to an interacting surface of the host station by        means of at least one electrical signal induced by at least one        inductor magnetic field in at least one electrical circuit of        the host device associated with said interacting surface,    -   saving said current position in a position history, said        position history comprising a set of positions of said at least        one mobile device over a sliding temporal window,    -   comparing, by means of said history, a change in the position of        said at least one mobile device relative to the interacting        surface of the host station with at least one reference movement        diagram, said reference movement diagram being associated with        at least one reference movement of the mobile device relative to        the interacting surface of the host station, and    -   triggering a command of the host station according to said        reference movement, if said change corresponds to said reference        movement.

A method according to the first aspect makes it possible to control ahost device for mobile devices based on gestures made by a usermanipulating a mobile entity.

The user is thus provided with an interface with the host device whichis intuitive and of low complexity since it does not require any itemdedicated to the interface (mouse, keyboard or other item) in additionto the mobile entities.

The determined position of the mobile entity may comprise at least oneof:

-   -   a distance between the mobile device and said interacting        surface,    -   a coordinate of the mobile device in a frame of reference        associated with said interacting surface, and    -   an orientation of the mobile device according to an axis        orthogonal to said interacting surface.

All movements in space of the mobile entity relative to the host devicemay thus be used to define a command of the host device.

An absence of movement for a predetermined period may also be consideredas a reference movement. Thus, for example, if the mobile device is leftimmobile for that predetermined period, an action associated with thatimmobility may be triggered.

The position history may for example be stored in a file, such as atemporary file, in random access memory or in lasting memory. Thehistory may however be stored in other forms (data queue of FIFO type,FIFO standing for “First In First Out”, an allocated memory, a database,etc.).

A method according to the first aspect may enable the use of the mobileentities as a user interface to be coupled with a display on a screenwhich may be either integrated into the host device or situated awayfrom it.

Thus, for example, the method may furthermore comprise the followingsteps:

-   -   displaying on a screen at least one contextual item for        selecting said command, said at least one contextual item being        displayed at a position on the screen representing the position        of said mobile device relative to said interacting surface,    -   selecting said contextual item according to a first        identification of a first reference movement, and    -   triggering said command according to a second identification of        a second reference movement.

Said interacting surface may be superposed on said screen. The screenmay also be situated away from the host station.

The detected movements may be of various kinds, thereby giving the usera variety of gestures to control the host device.

For example, the change in position of said mobile device comprises afast variation in the distance between the mobile device and theinteracting surface, and said reference movement is a click.

Said command may then comprise the activation of a selected action.

According to a further example, the change in the position of saidmobile device comprises a succession of fast variations in the distancebetween the mobile device and a reference position in a frame ofreference associated with said interacting surface, and said referencemovement is a shake.

Said command may then comprise the cancellation of an action in course.

According to another example, the change in the position of said mobiledevice comprises a slow rectilinear movement of the mobile devicerelative to said interacting surface, and said reference movement is aslide.

Said command may then comprise the variation of a slider according tothe movement of the mobile device.

According to another example, the change in the position of said mobiledevice comprises a rotation thereof relative to an axis orthogonal tosaid interacting surface, and said reference movement is a rotation ofthe mobile device between a first direction and a second direction.

said command may then comprise selecting a contextual item displayed ona screen and situated in said second direction.

According to embodiments, a prior step of receiving an activation signalgenerated by the mobile device further to the actuation of a userinterface on the mobile device makes it possible to activate thedetermination of the current position of the mobile device.

Thus, the recognition of the reference movement which ensues is onlycarried out only at the user's request, which makes it possible to savecomputing resources within the host device.

A second aspect of the invention concerns a computer program as well asa computer program product and a storage medium for such program andproduct, enabling the implementation of a method according to the firstaspect when the program is loaded into and executed by a processor, forexample a processor of a host device of a mobile device.

A third aspect concerns a host device configured for implementing amethod according to the first aspect.

For example, such a device comprises at least one interacting surfacefor interaction with at least one mobile device, said host devicecomprising a processing unit configured for the implementation of thesteps of a method according to the first aspect.

A fourth aspect concerns a mobile device.

For example, such a mobile device comprises at least one location moduleto generate an inductor magnetic field configured to induce anelectrical signal in at least one electrical circuit of a host device,said mobile device further comprising a user interface configured totrigger the sending, by the mobile device, of a command signal of thehost device.

According to an embodiment, said signal is a signal for activating thedetermination by the host device, of the current position of the mobiledevice relative to an interacting surface of the host device.

This signal enables the user to trigger a reference movement recognitionsequence. Such recognition on request enables computing resources of thehost device to be served.

According to another embodiment, said interface comprises a plurality ofsuccessive positions, and said signal is a signal representing a currentposition of the interface.

The interface may thus be a slider or a wheel. This type of interfacemakes it possible to use graphical interfaces enabling the user toselect values from a range of values or for instance items from a list.

According to still another embodiment, the device comprises at least twolocation modules, a first location module being installed in a main bodyof the mobile device, a second location module being installed in asecondary body of the mobile device, the secondary body being adapted tomove relative to the main body.

With such an embodiment, the user may perform gestures of rotation ofthe secondary body relative to the main body, thus making a referencemoment associated with a command.

A fifth aspect concerns a system comprising a host device according tothe third aspect and at least one mobile device comprising at least onelocation module for generating an inductor magnetic field configured toinduce an electrical signal in at least one electrical circuit of thehost device.

For example, the system comprises at least one mobile device accordingto the fourth aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

Other advantages, objects and features of the present invention willemerge from the following detailed description, given by way ofnon-limiting example, relative to the accompanying drawings in which:

FIG. 1 diagrammatically illustrates an example of architecture capableof implementing the invention;

FIG. 2 illustrates an example of a detection surface and of associatedlogic;

FIG. 3 diagrammatically illustrates the physical principle of inductivecoupling between a solenoid and a conductive loop of a detectionsurface;

FIG. 4 diagrammatically illustrates an interpolation mechanism making itpossible to compute the position of a solenoid placed on a detectionsurface, along a given axis, based on measurements obtained by a systemsuch as that described with reference to FIG. 2;

FIG. 5 illustrates a context for implementation of embodiments of theinvention;

FIGS. 6a, 6b, 6c and 6d illustrate example embodiments of mobiledevices;

FIGS. 6e and 6f illustrate the dimensioning of mobile devices;

FIG. 7a diagrammatically illustrates logic blocks of a location modulefor locating a mobile device of which the position and/or theorientation may be determined from a host device.

FIG. 7b illustrates an example of electronic implementation of the logicdiagram described with reference to FIG. 7a relative to a locationmodule for locating a mobile device of which the position and/or theorientation may be determined;

FIGS. 8a-8h illustrate embodiments of mobile device location modules;

FIGS. 9 and 10 illustrate examples of algorithms capable of being usedto sequentially activate a set of location modules and to compute thepositions and/or orientations of the corresponding mobile devices;

FIGS. 11a-11d illustrate reference movements of mobile devices;

FIGS. 12a-12g illustrate commands associated with reference movements;

FIG. 13 is a flowchart of steps implemented in embodiments;

-   -   and

FIGS. 14a-14c illustrate embodiments of mobile devices with a userinterface.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Host Device

With reference to FIGS. 1 to 4, a description is given of a host deviceand mobile devices able to be used for embodiments of the invention.

A general architecture 100 for implementation of embodiments isdiagrammatically illustrated by FIG. 1. For example, this architectureis applied in the context of a game application. The invention ishowever not limited to such an application. Details on this type ofarchitecture may be found in the document WO 2012/028827.

The architecture 100 comprises in a general manner a host device 105.The host device may for example take the form of a board. In the contextof the game application, a game board may be adapted to couple the uppersurface of the host device to a screen. This screen may for exampleenable information to be displayed for a user according to actionscarried out by the user on the host device.

To interact with the host device, the user may use mobile devices 110forming part of the architecture described here with reference toFIG. 1. In FIG. 1, five mobile devices are represented. However, theinvention cannot be limited either to the number of mobile devicesrepresented or to their form. For example, to interact with the hostdevice, or more specifically with the associated computer system, theuser may move the mobile devices.

To detect the interactions of the user, the host device comprises adetection layer 115 to detect the presence and/or the position and/orthe orientation of the mobile devices relative to that layer.

For example, the detection layer is coupled to a screen 120 and amagnetic layer 125 (the detection layer 115, the screen 120 and themagnetic layer 125 are substantially parallel here). A detection module130 of the host device makes it possible to detect the position and, ifnecessary, the orientation of the mobile devices as well as to implementone or more applications with which the user interacts.

The detection module is in particular in charge of managing thedetections of the positions and/or orientations of the mobile devices.To that end, this module may for example identify location modules (notshown) disposed in the mobile devices. For example, the detection moduleidentifies them one after the other then sends them an activation signalin order for them to emit, each in turn, an electromagnetic field. Thedetection module then employs an evaluation of their positions based onsignals induced in the detection layer by the emitted magnetic fields.

The detection module is for example inserted into a casing with theother components of the host device 105. Alternatively, it may be aremote module integrated, for example, in a computer or game console. Itmay be electrically powered by a rechargeable battery or via a mainsadaptor and have a set of conventional connections 135, for example anelectrical plug for a mains adaptor, and ports for USB, Ethernet, VGAvideo (VGA standing for Video Graphics Array) and/or HDMI (HDMI standingfor High Definition Multimedia In), where appropriate, in particular ifa screen is associated with the detection layer. It may furthermorecomprise a wireless communication module, for example a wirelesscommunication module of WIFI or Bluetooth type enabling interaction withanother computer system and/or access to data via a communicationnetwork.

The detection module 130 comprises a computing module and a controlmodule for position sensing and detection detailed below. The computingmodule is provided here with a central processing module (or CPU), agraphics processing unit (or GPU), memory components (RAM, standing forRandom Access Memory, ROM, standing for Read Only Memory and/or memoryof Flash type) to store the programs and the variables necessary for theimplementation of the invention as well as an audio processing module,in the form, for example, of a chipset.

According to a particular embodiment, the hardware module 130 is notintegrated into the host device 105 but is linked to it. It is forexample a device of smartphone type connected to the board 105.

The control module for position sensing and detection sequentiallyactivates, for example by radio, each location module of which theposition is to be determined or controls such a sequential activation.

After activation, each location module here emits an electromagneticfield sensed by the detection surface. Thus, a location module may alsobe seen as a magnetic field generating module. The generation of themagnetic field enables the host device to locate the mobile device.

Once the electromagnetic field has been sensed, the detection surfacesends information to the position detection and sensing module making itpossible to compute the position of a location module, for example of(x, y, z) type. As described below, when several location modules areassociated with the same mobile device, it is possible, based on thepositions of those location modules, to determine orientation parametersof that mobile device, for example in the form of angles. The positionsand/or orientation of all the mobile devices of which the positionand/or orientation are to be determined are then sent to the computingmodule which uses them to manage the interactivity with the applicationconsidered.

FIG. 2 illustrates an example of a detection layer and associated logicaccording to one embodiment.

The detection layer 115 comprises a mesh in the form of rows and columnsconstituting a conductive grid. The latter comprises a set of conductiveloops along two orthogonal axes. Each loop is a discrete sensor enablingan induced signal to be measured, for example the magnitude of aninduced current or the voltage induced by an electromagnetic field. Theelectromagnetic field is for example generated by a radiating element,such as a solenoid belonging to a mobile device of which the positionand/or the orientation must be computed positioned in the vicinity ofthe upper surface of the host device, and more particularly in thevicinity of the detection layer.

By way of illustration, it is assumed here that a solenoid is placed inthe vicinity of the position marked 200 in FIG. 2, at the intersectionof the loops 205 and 210 of which one end is connected to a ground andthe other end is connected to the electronic components used to computea position. When the solenoid situated at position 200 is powered, itgenerates a magnetic field which induces electric currents in the loops205 and 210 which may be analyzed and compared with the currents inducedin the other loops. It is thus possible, by inductive coupling betweenthe solenoid and the grid and by measurement of induced current, todetermine the position of the solenoid relative to the conductive gridand thus relative to the detection layer.

Multiplexers 215 and 220 are connected to each loop of each of the twoaxes of the grid, that is to say here to each of the vertical andhorizontal loops, respectively. The outputs from the multiplexers 215and 220 are connected to the automatic gain controllers (AGCs) 225 and230, respectively, of the control module for position sensing anddetection, here referenced 130-1, of the detection module. The outputsignals from the automatic gain controllers 225 and 230 are first of alldemodulated in the demodulators 235 and 240, respectively. Thedemodulation produces a direct current (or DC) signal proportional tothe original sinusoid supplemented with alternating current (or AC)components that are multiples of the fixed frequency of the magneticfield emitted by the solenoid.

According to a commonly used configuration, the computing module, herereferenced 130-2, of the detection module 130 controls the multiplexers215 and 220 in order to sequentially activate the loops, that is to sayto activate a loop n+1 after a loop n. When the last loop has beenreached, the processor initiates a new cycle and controls the activationof the first loop.

A band-pass filter may be employed in each automatic gain controller 225and 230 to eliminate the undesirable harmonics from the demodulatedsignal as well as the electromagnetic background noise. This filteringmakes it possible to refine the measurements of the signals coming fromthe multiplexers 215 and 220, which are demodulated in the demodulators235 and 240 then digitized in the digital/analog converters (DACs) 245and 250, respectively.

The digital values obtained are sent to the central processing unit(CPU) 255 of the computing module 130-2 to be stored in memory. Asillustrated, the central processing unit 255 controls the demodulators235 and 240.

After the values have been stored in memory, the central processing unitincrements the address of the multiplexers in order to carry out thedigitization of the signals coming from the following loops. When a lastloop has been attained, the central processing unit reinitializes theaddress of the multiplexer corresponding to the value of the first loopof the axis considered.

At the end of a cycle, the central processing unit has stored in memory,for each axis, the same number of digital values as there are adjacentloops close to the position of the solenoid. Based on these values, thecentral processing unit computes the position of the solenoid byinterpolation as described below.

It is to be noted here that the ground connection of the loops may beprovided by strips of metal positioned between the different loops inorder to protect them from electromagnetic interference. An alternativeconsists of disposing a uniform ground plane under the conductive grid.

Furthermore, the control module for position sensing and detection 130-1here comprises an emitter 260, controlled by the central processing unit255 of the computing module 130-2, enabling a location module of amobile device to be activated. By way of illustration, the centralprocessing unit 255 sends to the emitter 260 an identifier of a locationmodule to activate. This identifier is coded then sent in the form of adigital or analog radio signal. Each location module receiving thisactivation signal may then compare the identifier received with its ownidentifier and activate itself if the identifiers are identical.Alternatively, the central processing unit 255 sends to the emitter 260a general activation command which is coded then sent in the form of adigital or analog radio signal.

The emitter 260 is linked to an antenna 265 enabling the sending of acommand signal used by the mobile entities such as an energy source andfor activating the location modules. The antenna 265 may be placed onthe detection surface 115, for example around the loops 205 and 210. Theloops 205 and 210 may be used to form the antenna 265. For suchpurposes, a switch is used to determine the sending or receivingfunction of the loops 205 and 210 (these latter are then, according tothe position of the switch, linked to the multiplexers 215 and 220 or tothe emitter 260).

As described below, the emitter 260 may in particular comprise a readerof RFID type.

Thus, to estimate the position of a set of location modules, eachlocation module is sequentially activated and, for each of theseactivations, according to the embodiment described here, a cycle iscarried out on each set of loops.

Several detection layers may be combined with each other in a sameplane, the resulting area of the detection layer being the sum of theareas of the detection layers combined. For such purposes, one detectionlayer is considered as “master”, the others being considered as slaves.The sequential activation of the mobile devices is managed by the“master” detection layer which preferably receives the positionscomputed by the detection modules associated with each slave detectionlayer and consolidates them by producing a table containing thecoordinates and angles of freedom of the location modules.

FIG. 3 diagrammatically illustrates the physical principle of inductivecoupling between a solenoid and a conductive loop of a detection layer.

Each mobile device of which the position and/or the orientation are tobe computed comprises at least one solenoid of which the axis is,preferably, oriented towards the detection surface.

The solenoid 300 is passed through by an alternating current andgenerates (or emits) an electromagnetic field which propagates towardsthe detection surface, in particular, in this example, towards the loop210. The loop 210, receiving an electromagnetic field coming from thesolenoid 300, couples with the solenoid 300. It is then possible tomeasure an alternating current signal at the terminals of that loop,referenced 305.

The coupling between the solenoid 300 and the loop 210 may be expressedin the form of the following relationship,

$R = {\frac{k}{D^{2}}E}$

where

E designates the voltage at the terminals of the solenoid 300, Rdesignates the voltage of the signal received at the terminals 305 ofthe receiving loop 210, D is the distance between the solenoid 300 andthe receiving loop 210 and k is a constant linked to intrinsic factorsof the system comprising the solenoid and the receiving loop, inparticular the number of turns of the solenoid and the size of the loop.

FIG. 4 diagrammatically illustrates an interpolation mechanism making itpossible to compute the position of a solenoid placed in the vicinity ofa detection layer, along a given axis, based on measurements obtained bya system such as that described with reference to FIG. 2.

It is assumed here that the solenoid is situated in the vicinity ofvertical loops B3, B4 and B5, positioned according to the x-coordinatesX3, X4 and X5, the voltages measured at the terminals of the loops beingdenoted V3, V4 and V5, respectively. The solenoid is to be found here ata position, along the x-axis, denoted XS.

The coordinates X3, X4 and X5 may be obtained by the central processingunit from an identifier of the corresponding loop (these values arepredefined according to the routing diagram of the detection surfaceand, preferably, are stored in a non-volatile memory).

The portion of curve 400 represented in FIG. 4 illustrates the variationin voltage for the position XS of the solenoid according to thepositions of the loops coupled with the solenoid, extrapolated from thevalues measured by the loops B3, B4 and B5. It may be assimilated to aquadratic function of parabolic type. This local approximationcorresponds, in practice, to the phenomenon of electromagnetic couplingbetween a solenoid and loops of a conductive grid.

The following relationships illustrate this property.V3=a(X3−XS)² +bV4=a(X4−XS)² +bV5=a(X5−XS)² +bin which a and b are constants, a being a constant less than zero (a<0).

Furthermore, given the assumption of a quadratic function, therelationships between the x-coordinates X3, X4 and X5 may be expressedin the following form,X4−X3=X5−X4=ΔXX5−X3=2ΔX

(ΔX representing the distance between the x-coordinates X3 and X4 andbetween the x-coordinates X4 and X5).

It is thus possible to interpolate the position of the solenoidaccording to the following formula:

${XS} = {{X\; 3} + {\frac{\Delta\; X}{2}\frac{{{3V\; 3} - {4V\; 4} + {V\; 5}}\;}{{V\; 3} - {2V\; 4} + {V\; 5}}}}$

It is also possible, according to the same logic, to determine theposition of the solenoid according to the y-axis.

Furthermore, the distance between the solenoid and the loop (that is tosay the altitude of the solenoid relative to the detection surface) maybe defined according to the following relationship,

$D = \sqrt{\frac{k}{R}E}$

The distance D is thus a function of the value R representing thevoltage at the terminals of the loops considered of the detectionsurface. It may be extrapolated from the measurements made. It is to benoted that the accuracy of this distance computation is in particularlinked to the stability of the signal E emitted by the solenoid of whichthe value must be as constant as possible over time, which requires astabilized supply in the location module which must not drop as thebattery discharges. This may be ensured by a voltage regulator of thelocation module.

As indicated earlier, the electronics for activating and locating themobile entities is electrically supplied by induction. The antenna usedto harvest the energy may also be used for activating and synchronizingthe mobile entity. According to embodiments, the supply of the locationmodules of the mobile entities is made by a remote powering module of acircuit of RFID type. The utilization of an RFID type technology maythus be used to supply location modules and, the case arising, ascommunication means to enable them to be activated or synchronized.

For these purposes, the emitter 260 represented in FIG. 2 (or moregenerally the position detection controlling module) uses a reader ofRFID reader type enabling an embodiment for communication andsynchronization of the location module via the RFID technology. Thecommunications may then be made by operations of reading and writing ina non-volatile memory of an RFID type circuit carried by the mobileentities. Such memories are for example accessible by the host device byRFID type accesses as well as by microcontrollers carried in the mobileentities by direct electrical links. A synchronization may in particularbe made by a specific modulation of the amplitude of the RFID carrier.

Thus, for example, the electronics of the host device comprise an RFIDtype reader, that is to say a system enabling access through reading andwriting to RFID type components, or RFID tags, situated in the vicinityof the host device. These electronics here comprise at least oneconductive coil covering the whole of or part of the interacting surfaceof the host device, used as RFID emitter/receiver antenna.

The average magnetic power emitted by the RFID antenna of the hostdevice is of a level such that it enables remote powering by magneticinduction of the electronics of the mobile entities situated in theimmediate vicinity of the RFID antenna.

It is to be noted here that the RFID reader and the mobile entities mayexploit one of the numerous RFID standards and their derivatives such asthe standards ISO/IEC 15693, ISO 18000-3, ISO 18000-4, ISO 18000-7,ISO/IEC 14443, ISO/IEC 18092 (better known under the name of NFC,standing for Near Field Communication), ISO/IEC 21481 (also known underthe name of NFC).

The central processing unit used to control the sensing surface, forexample the central processing unit 255, is also used here to controlthe RFID reader. It may also temporally control the activation and thedeactivation of the production of the electromagnetic field for remotepowering in phase with a cycle of duration T1 of a commonsynchronization signal.

According to embodiments, at least some of the mobile entities contain anon-volatile dual-port memory. This latter is accessible here by an RFIDtype reader, via wireless communication, and also by a localmicrocontroller, via a wired connection, for example a connection inaccordance with the I²C bus standard (I²C standing for Inter IntegratedCircuit). Whereas this dual-port memory may be used to trigger theactivation of a mobile entity and thus enable its location, it may alsobe used for other purposes while providing a particular communicationmeans between a mobile entity and the sensing surface.

The dual-port memory of a mobile entity may be accessible throughreading and writing by the RFID type reader of the host device. It formsa communication means between the logic of the host device and amicrocontroller carried in a mobile entity. The microcontroller is,preferably, altered to each reading and writing request received via thewireless communication protocol. Further to the reception of anindication of reception of a request, the microcontroller mayinterrogate that memory to determine whether such a request is addressedto it, the access type (writing or reading access) and the memoryaddress concerned by the access request.

Furthermore, each mobile entity contains, in non-volatile memory, aunique identifier which is stored, for example, over 64 bits. Accordingto a particular embodiment, this unique identifier is that known underthe name of UID (standing for Unique IDentifier) of an electroniccomponent accessible using an RFID type reader. Such an identifier mayin particular be in accordance with a standard such as the ISO 15693,ISO 18000-3 and ISO14443 standards. Thus, an RFID type reader makes itpossible to detect the arrival of new mobile entities and to identifythem in unique manner by their identifier.

As described below with reference to FIGS. 8a-8h , the logic associatedwith the host device may determine and allocate a time out value foreach detected location module. A time out value here represents a periodof time after which a location module must emit a location signalfurther to the detection of a synchronization signal. The time out valueallocated to a newly detected location module may be a free time outvalue (previously allocated to a location module which is no longerdetected).

For these purposes, the RFID type reader may address the determined timeout value to a dual-port memory of a location module in a writingrequest. By way of illustration, a computer system associated with thehost device may interrogate a database, local or remote, with theidentifier of the location module as access key. Such a database forexample makes it possible to obtain the list of the functionalcharacteristics of the mobile entity. Thus, for example, this databasemay be used to determine whether the mobile entity comprising thelocation module considered has motors, actuators, display devices, soundproduction devices, sensors and/or switches. The list of thefunctionalities obtained may in particular be used to determine thenature of exchanges of commands and data that are possible between thecomputer system and the mobile entity.

The non-volatile dual-port memory used to store a location moduleidentifier are, preferably, integrated with a remote powering modulewithin the same component. Such components are available. Thus, forexample, the company ST Micro Electronics manufactures a component underthe reference M24LR16E which provides dual-port functions, of wirelessinterfacing and energy recovery.

In a mobile entity, such a circuit is advantageously linked to amicrocontroller by an I2C type bus.

Furthermore, each mobile entity comprises one or more resonant circuitsas well as at least one switch to enable the emission of locationsignals. The switch is for example controlled by the microcontrollerwhich thus triggers the resonating or stopping of resonating enablingthe location of the corresponding location module. It is to be notedhere that the use of two resonant circuits enables a mobile entity to belocated and to determine the orientation thereof. A single resonantcircuit may be used if, alone, the position of the mobile entity is tobe determined. Alternatively, more than two resonant circuits may beused, in particular to improve the estimation of the position and/or theorientation of the mobile entity.

Other embodiments may be envisioned for the logic associated with thedetection layer. It is possible for example to refer to the document WO2012/028827.

Context for Implementation

After having described the general architecture of a host deviceenabling the implementation of embodiments, a context of implementationof embodiments of the invention is described below.

FIG. 5 diagrammatically illustrates a host device 500 such as thatalready described in detail above.

A mobile device 501 is disposed on the upper surface (or host surface orinteracting surface) 502, of the host device. This mobile devicecomprises two faces 503 and 504. The mobile device 501 is disposed onthe host surface on the face 503, the latter is not thus visible in FIG.5.

The mobile device 501 comprises two interacting surfaces whichcorrespond to the faces 503 and 504. It is assumed that the user mayinteract with the host device, via the mobile device 501, by placing thelatter on the host surface on one or other of its faces. According tothe invention, the host device is then able to determine the face onwhich the mobile device is placed. In the illustrated example, themobile device has the general shape of a disc. For example, the mobiledevice may represent a token which the user can place on one or other ofits faces.

Another mobile device 505 is placed on the host surface. This mobiledevice has the general shape of a cube. It thus comprises six facesnumbered “1” to “6”. These faces constitute interacting surfaces forinteraction with the host surface. In the example represented, the diceis placed on its face numbered “4” and only the faces numbered by “1”,“3” and “5” are visible.

For example, the user implements on the host device an application, or agame, requiring the use of a die. The user may then throw the die on thehost surface and, according to the face on which the die falls, the hostdevice can deduce therefrom the number thrown. The host device detectsthe interacting surface in contact with the host surface and deduces theface of the die presented to the user. In such an application, themagnetic layer discussed in the presentation of the host device may bedeactivated for the time in which to throw the die, or even beeliminated.

The mobile devices 501 and 504 described above have purely illustratefunctions. The present invention is not to be limited to mobile deviceshaving these shapes or having these functions.

Mobile Entities

FIGS. 6a, 6b, 6c and 6d diagrammatically illustrate respectively fourexamples of mobile devices according to embodiments. The invention isnot limited to these examples. These examples may be combined.

The mobile device 600 represented in FIG. 6a comprises a single locationmodule 601. The mobile device has the general shape of a disc, forexample to serve as a token. The mobile device could however haveanother shape.

As illustrated, the device comprises a solenoid of which the radial axisis perpendicular to the plane of the face 602 (or interacting surface)with which the detection module is associated. Thus, the electromagneticradiation (represented by an arrow) of the solenoid propagates optimallytowards that face.

The three-dimensional position of the mobile device 600 may be computedas described above. Based on the computed position of the solenoid ofthe location module 601 and knowing the position of that module in themobile device 600, it is possible to deduce therefrom the position ofthe latter, that is to say the position of a point of reference of thatmobile device relative to a detection layer of a host device. Whenseveral mobile devices are present on the detection surface, theposition of each mobile device is determined sequentially.

The mobile device 603 represented in FIG. 6b comprises two locationmodules 604 and 605. These location modules may be independent modules.By way of illustration, the mobile device has the general shape of adisc. In FIG. 6b , the circular faces 606 and 607 of the disc are notvisible.

The radial axis of each solenoid of each location module isadvantageously perpendicular to the plane of the face (or interactingsurface) with which the location module is associated. Thus, the radialaxis of the solenoid of the module 604 (respectively 605) isperpendicular to the face 606 (respectively 607). In this way, theelectromagnetic radiation of the solenoids propagates optimally towardsthe faces of the mobile device.

The mobile device 608 represented in FIG. 6c comprises six locationmodules. These location modules may be independent modules. By way ofillustration, the mobile device has the general shape of a cube. Alocation module is associated with each face of the mobile device. InFIG. 6c , the cube is seen from the front and only four location modules609, 610, 611, 612 are represented. The mobile devices respectivelyassociated with the front face and with the back face of the cube arenot represented in the interest of clarity of the Figure.

The radial axis of each solenoid of each location module isadvantageously perpendicular to the plane of the face (or interactionsurface) with which the location module is associated. Thus, the radialaxes of the solenoids of the modules 609, 610, 611 and 612 arerespectively perpendicular to the faces 613, 614, 615 and 616. In thisway, the electromagnetic radiation of the solenoids propagates optimallytowards the faces of the mobile device.

The mobile device 617 represented in FIG. 6d comprises four locationmodules. These location modules may be independent modules. For example,the location modules comprise solenoids. By way of illustration, themobile device is substantially cube-shaped. It thus comprises six faces618-623. The four location modules 624-627 are respectively disposed atthe location of the four corners A, B, C and D of the cube.

According to the disposition of the location modules in the mobileentity represented here, it is the combination of the detection of atleast two location modules at the detection layer of the host devicewhich makes it possible to define the face of the mobile device which isin interaction with the host station.

When the location modules 624 and 626 (disposed at the corners A and C)are detected by the detection layer, the face 618 is defined as beingthat in interaction with the host station.

When the location modules 624 and 625 (disposed at the corners A and B)are detected by the detection layer, the face 619 is defined as beingthat in interaction with the host station.

When the location modules 626 and 625 (disposed at the corners C and B)are detected by the detection layer, the face 620 is defined as beingthat in interaction with the host station.

When the location modules 626 and 627 (disposed at the corners C and D)are detected by the detection layer, the face 621 is defined as beingthat in interaction with the host station.

When the location modules 624 and 627 (disposed at the corners A and D)are detected by the detection layer, the face 622 is defined as beingthat in interaction with the host station.

When the location modules 625 and 627 (disposed at the corners B and D)are detected by the detection layer, the face 623 is defined as beingthat in interaction with the host station.

With this disposition of the location modules, it is possible to reducethe complexity and the cost of manufacture of the mobile entity since alower number of location modules is required.

Other forms of mobile devices as well as other dispositions of thelocation modules may be envisioned.

When the mobile device comprises a plurality of location modules, it mayfurther comprise a processing unit (not shown) to control them. Forexample, this processing unit may receive from the host device anactivation signal, then trigger a sequence for activation of thelocation modules.

When the mobile device is of reduced size and comprises several locationmodules with solenoids, the intensity of the radiated magnetic fieldmust be determined such that two spatially close solenoids do not createperturbations for each other's location module.

FIG. 6e illustrates this problem diagrammatically. Two faces of a mobiledevice are represented in the vicinity of a detection layer 628 of ahost device. The face 629 is placed on the detection layer whereas theface 630 is orthogonal to it. Solenoids 631 and 632 belonging tolocation modules are respectively associated with the faces 629 and 630.The lines of magnetic flux coming from the solenoids are represented.

The lines of flux coming from the solenoid 631 pass through thedetection layer thereby inducing an electric current in the detectionlayer. The host device thus detects the presence of the face 618.However, on account of the proximity of the solenoid 632, the flux linescoming therefrom also pass through the detection layer. There is thus arisk of the host device detecting two interacting faces (or surfaces) inthe same sequence for activation of the location modules. This riskexists in particular if the intensities of the magnetic fields generatedare high.

To reduce this risk, account should be taken, in the dimensioning of themobile device, of the overlap of the magnetic fields generated by thelocation modules that are close.

FIG. 6f illustrates one solution to this effect. This Figure reproducesthe devices of FIG. 6e , with the exception of the solenoids 631 and 632which are respectively replaced by solenoids 631′ and ‘632’. Thesolenoids 631′ and 632′ have smaller dimensions and emit more “compact”lines of magnetic flux. Thus, as can be noted in FIG. 6f , the fluxlines coming from the solenoid 632′ do not pass through the detectionlayer. Only the flux lines coming from the solenoid 631′ pass throughthat layer. The host device cannot thus detect both faces 629 and 630 inthe same sequence.

The dimensions of the solenoid may thus be chosen in particularaccording to the dimensions of the faces with which they are associatedso as to minimize the risk referred to above. Generally speaking, itshould be ensured that the lines of flux coming from a solenoid do notpass through the detection layer (or do so only a little) when the faceassociated with it is not in interaction therewith.

For the mobile devices comprising a plurality of location modules, eachlocation module may be activated independently from the others,sequentially. It is thus possible to determine the position of themobile device by determining the position of each solenoid of thelocation modules and by knowing their respective position in the mobiledevice. Similarly, it is possible to know the orientation of this mobiledevice based on the relative positions of the solenoids of the locationmodules and their position in the mobile device.

It should be observed here that the use of the coordinates of thesolenoids of the location modules, in the plane of the detection layerof the host device with which the mobile device interacts, makes itpossible to determine the orientation of the mobile device relative tothat plane whereas the use of the altitude of the solenoids of thelocation modules relative to that plane makes it possible to compute thepitch of the mobile device.

It is to be noted here that mobile devices comprising a single locationmodule and comprising two location modules may be used conjointly on thesame host device provided that the control module for position sensingand detection used is capable of activating each solenoid independentlyfrom the others.

The sensing of the orientation of mobile devices may thus be obtained byproviding each mobile device with at least two location modules (whichmust not be aligned along a perpendicular to the plane of the detectionlayer) and by defining an identification rule for those locationmodules.

The roll of a mobile device may be determined by providing the latterwith two complementary location modules (four location modules are thenused) and by adding to the identification rule for those modules toassociate identifiers of those four location modules with a mobiledevice.

Based on the three-dimensional positions of four location modules of amobile device, it is possible to compute its six degrees of freedom.

It is also possible, by associating three location modules with a mobiledevice, forming an equilateral triangle, to approximately compute itssix degrees of freedom.

The sequential activation of the location modules by a control modulefor position sensing and detection, makes it possible to estimate theposition and/or the orientation of a plurality of mobile devicesprovided with those location modules.

When a location module receives an activation command dedicated to it,it triggers an electromagnetic emission. The detection system, knowingthe identification of the location module in course of emission, canthen link the computed position information to the identifier of thelocation module.

The control module for position sensing and detection is thus in chargeof sequentially activating one electromagnetic emission per locationmodule, of retrieving one by one all the positions and, knowing thelinks between the identifiers of the location modules and identifiers ofthe mobile devices, of computing orientations, where required, in orderto associate positions and/or orientations with the identifiers ofmobile devices. It thus constructs a table containing, for each mobiledevice, an identifier, an x-coordinate, a y-coordinate and, preferably,an altitude in a frame of reference of the detection surface as well as,where required, values for yaw, pitch and roll.

The sequential activation of the electromagnetic emission of thedetection modules enables the use of a single emission frequency for allthe mobile devices managed by the system. Different algorithms foractivation may be used by the control module for position sensing anddetection. It is thus possible to always activate all the locationmodules, to activate a subset of location modules, that subset being,for example, defined by programming via the computing module (such animplementation makes it possible in particular to reduce the overallduration of the full activation sequence of the parts) or to activatethe location modules according to the context. This last solution inparticular makes it possible to manage the fact that certain mobiledevices may leave the detection surface and that their positions and/ororientation is no longer required to be computed. A secondary loop mayhowever preferably enable surveillance of their possible reintegrationonto the detection surface and the ensuing need to again sense theirposition and/or orientation. This embodiment makes it possible tooptimize the overall duration of the sequence for activation of all thelocation modules to be activated.

The general architecture of a mobile device is described with referenceto FIG. 7a . A mobile device comprises a location module of which thelogic blocks are represented diagrammatically. The location module makesit possible to determine, based on a system such as that describedabove, the position and/or the orientation of the mobile device.

The location of the mobile device is carried out by means of thegeneration of an electromagnetic field.

Such a mobile device is, preferably, autonomous both as regards itselectrical supply and as regards the reception of signals forcontrolling electromagnetic emission.

The location module 700 thus comprises an electrical supply module 705providing a voltage for all the components of the location module aswell as a command reception and detection module 710 which receives anddemodulates a signal, for example a HF signal, emitted by an externalmodule for controlling position sensing and detection to determinewhether the signal received concerns the activation of that locationmodule. As described above, such a detection may be carried out by thecomparison of a received identifier with an identifier stored in memoryin advance.

The location module 700 further comprises a switch 715, controlled bythe command reception and detection module 710, as well as a selectiveamplifier 720 controlled by the switch 715. Lastly, the location module700 comprises a local oscillator 725 generating a frequency, which ispreferably fixed, stable and of square-wave type, and a solenoid 730.

The selective amplifier 720 generates, according to the position of theswitch 715 and based on the signal from the local oscillator 725, asinusoid voltage at the terminals of the solenoid 730, enabling thesolenoid 730 to generate sufficient radiation power.

Several types of electrical supply for the location module may be used.The supply may be obtained from a rechargeable battery and a standardcontrol circuit. It may also be obtained from a battery and a voltageregulator making it possible to obtain a constant voltage throughout arange of use of the battery. This solution is particularly advantageouswhen the system must compute the altitude of mobile devices utilized.

The supply may also be provided indirectly, by remote powering.According to this embodiment, a layer of dedicated radiating solenoidsis placed under the detection surface. These solenoids are passedthrough by a sinusoid signal and the power emitted by each solenoid issufficient to remotely power the location modules positioned above it.The location modules are also equipped with a solenoid for receiving, byinduction, the signal emitted by the solenoids present under thedetection surface.

The remote powering may also be coupled with the use of a high capacitycapacitor which is charged from the solenoid of the location module. Thecapacitor is then used as a voltage source to supply the other modules.Alternatively, the remote powering may be coupled with the use of abattery present in the mobile device, for example a lithium battery. Thesolenoid of the location module then continually recharges that batteryas soon as an induced current passes through it. A charge/dischargeprotection circuit is advantageously associated with the battery inorder for it to remain within its range of acceptable voltages. Asindicated earlier, if the altitude of mobile devices is to be evaluated,the voltage source is, preferably, regulated in order for the supplyvoltage to be constant for a duration of use of that voltage source,that is to say for an estimation of position and/or orientation of themobile device.

The mobile devices situated on a detection surface and used conjointlymay use different types of power supply.

Furthermore, when a mobile device comprises more than one locationmodule, certain components, in particular the electrical supply, may becommon to some or all of the location modules.

FIG. 7b illustrates an example of electronic implementation of the logicdiagram described with reference to FIG. 7a relative to a locationmodule for locating a mobile device of which the position and/or theorientation may be determined.

The circuit diagram illustrated in FIG. 7b concerns an analog embodimentwith transmission of N carriers by the control module for positionsensing and detection, N representing the maximum number of locationmodules for which the positions can be computed by the system.

The command detection and reception module 7110 is here directed todetecting the frequency of the carrier associated with the locationmodule considered. It comprises, in this example of implementation, areception antenna 7100 and a network LC, comprising a capacitance 7102and an inductance 7104, tuned to an emission frequency of the controlmodule for position sensing and detection. It also comprises a diode7106 having the task of eliminating the negative component of the signalas well as a low-pass RC filter, comprising a resistor 7108 and acapacitor 7111, having the task of eliminating the carrier. If thecarrier is present, a signal is output from the filter whereas if thecarrier does not correspond to the location module considered, thesignal is zero at the output from the filter. The command reception anddetection module 7110 further comprises a switching transistor 7112,actuating the switch 7115 via a resistor 7114 which enables theselective amplifier 7120 to be activated. The switching transistor 7112is here linked to the RC circuit via a resistor 7116.

Such an implementation is directed to activation signal receptionaccording to amplitude modulation. However, other embodiments such asreception with frequency modulation or reception with phase modulationmay be employed.

The switch used is, for example, an HC 4066 switch from the companyTexas Instruments. It makes it possible to activate or deactivate theselective amplifier. The activation is carried out when the switch isopen, that is to say when the selective amplifier is connected to thepower supply 7105.

As described above, the local oscillator 7125 generates, preferably, asquare-wave signal of which the frequency is compatible with theconductive loops of the detection surface (these loops being dimensionedto receive a specific frequency). It comprises an oscillator 7118 here,for example an LTC 1799 oscillator from the company Linear Technology,coupled to the resistor 7120 here having a value of 4 kOhms to define anoscillation frequency of 250 KHz compatible with the frequency detectedby the loops of the detection surface.

The selective amplifier 7120 makes it possible to convert the squarewave signal generated by the local oscillator 7125 into a sine wavesignal. It furthermore ensures an optimum gain for the frequency of thelocal oscillator and enables the required magnitude of the sine wavesignal passing through the solenoid 7130 and thus the optimumelectromagnetic radiation towards the detection surface used.

The selective amplifier is produced here from a switching transistor7124, capacitors 7126 and 7128 as well as from the network of resistors7130 to 7138. The value of the capacitor 7128 is for example 33 μFwhereas the value of the resistor 7130 is 2 kOhms, the resistors 7132,7134, 7136 and 7138 1 kOhm and the resistor 7138 100 kOhms. Thus, thetimes for establishing and cutting-off the selective amplifier 720 arethe shortest possible.

The command detection and reception module 7110 may be embodiedaccording to variants other than that described above. In particular,beyond the analog embodiment with transmission of N carriers by thecontrol module for position sensing and detection, it is possible toimplement an analog embodiment using a single carrier containing asignal useful for the activation of a location module. According to thisvariant, a useful signal of which the frequency must be detected toactivate or not activate a location module is available at the output ofthe low-pass RC filter. This signal may, for example, be filtered in aband-pass filter of which the resonant frequency is tuned to thespecific activation frequency of the location module considered. Theoutput of this band-pass filter is then sent to a switching transistorwhich activates the analog switch enabling the activation of theselective amplifier.

Alternatively, a digital embodiment with transmission of a singlecarrier containing a digital useful signal for the activation of alocation module may be used. According to this variant, a useful signalis available at the output from the low-pass RC filter. This signal istypically a square wave signal containing digital information coded overseveral bits enabling the activation of a plurality of location modules.Each location module is equipped with a microcontroller which decodesthat signal and, according to the encoded value and a predeterminedvalue, activates the analog switch and thus the selective amplifier.

Other communication protocols such as Wi-Fi, ZigBee or Bluetooth may beused to send an activation command.

The pair formed by a local oscillator and a selective amplifier procurescertain advantages. In particular, as the local oscillator is alwaysactive, it is not necessary to activate and deactivate it. Furthermore,the selective amplifier used is the device which operates by switching(it is powered or not according to the position of the analog switch).Such an implementation thus enables a very short activation anddeactivation time for the selective amplifier and makes it possible tooptimize the switching time and thus the overall cycle time (one cyclecorresponding to the activation/deactivation of all the locationmodules).

It is however possible to implement simpler variants of oscillators ableto replace the local oscillator and selective amplifier pair, typicallyan assembly known as a Clapp or Colpitts type arrangement.

Below, variants are described in which the mobile entities are remotelypowered, as already referred to in more detail in the description.

FIG. 8a illustrates a first variant embodiment of an electronic circuit8000 of a mobile entity. As illustrated, the circuit 8000 comprises astandard component 8005 providing functions of RFID type by integratinga dual-port memory called an RFID chip, a microcontroller 8010 and tworesonant circuits 8015-1 and 8015-2, generically referenced 8015. Thecircuit 8000 also comprises an antenna 8020 of RFID type adapted to thecharacteristics of the circuit 8005. The antenna 8020 is typically acoil linked to the circuit 8005 via two links called AC0 and AC1 (ACstanding for antenna coil).

Two resonant circuits are implemented, sequentially, to enable theposition and orientation of the mobile entity to be determined. In otherwords, the mobile entity here comprises two location modules, theselocation modules having a part in common (basically comprising the RFIDcircuit, the RFID antenna and the microcontroller) and distinct parts(basically comprising the resonant circuits).

The RFID circuit 8005 is connected here to the microcontroller 8010 by abus of I2C type comprising a serial link for a clock signal called SCL(for Serial CLock) and a serial link to send data called SDA (for SerialData). The electrical supply terminal of microcontroller 8010, heredenoted Vcc, like that of the resonant circuits 8015-1 and 8015-2, isconnected to the terminal of the RFID circuit 8005 delivering a voltage,here denoted Vout. In a conventional manner, the terminal of the RFIDcircuit 8005 delivering a voltage is linked to a reference terminaldenoted Vss by a capacitor enabling electrical peaks to be absorbed.

Furthermore, the synchronization signal of the microcontroller, used tocontrol the triggering or stopping of the resonance (enabling thelocation of the mobile entity) is connected to a state terminal of theRFID circuit, denoted state here.

As the RFID circuit 8005 is linked to the RFID antenna 8020, it canreceive electrical energy from an RFID reader and exchange data with thereader, according to reading and writing requests, in particular toupdate its memory. As the output Vout of the RFID circuit 8005 is linkedto the supply terminals Vcc of the microcontroller 8010 and of theresonant circuits 8015-1 and 8015-2, these circuits may be electricallysupplied and used.

According to one example, the state terminal of the RFID circuit 8005indicates, by a first logic state, for example the value 1, that theRFID circuit is receiving and processing a reading or writing request,or, more generally, that it is performing a predetermined task. In theopposite case, the state terminal of the RFID circuit 8005 is in asecond logic state, for example the value 0. Thus, on account of theconnection of the synchronization terminal of the microcontroller 8010to the state terminal of the RFID circuit 8005, one of the resonantcircuits 8015-1 or 8015-2 may be activated by the microcontroller 8010,immediately or on a differed basis, according to a state of the RFIDcircuit 8005. In other words, a resonance and thus an electromagneticemission is triggered (after a predetermined time which may be zero)when the state terminal of the RFID circuit 8005 is in the first logicstate and stopped (also after a predetermined time which may be zero)when the state terminal of the RFID circuit 8005 is in the second logicstate. In other words, the RFID circuit 8005 has the task of controllingthe triggering or the stopping of the resonance (enabling the locationof the mobile entity).

It is to be noted here that the activation of the resonant circuits may,for example, be carried out sequentially according to a predeterminedtime offset (one of the resonant circuits may be activated after a firstpredetermined delay following the synchronization signal and the otherresonant circuit may be activated after a second predetermined delayafter the synchronization signal.

FIG. 8b illustrates a second variant of an electronic circuit 8100 of amobile entity. Like the circuit 8000, the circuit 8100 comprises astandard component 8105 providing functions of RFID type and integratinga dual-port memory (RFID component), a microcontroller 8110 and tworesonant circuits 8115-1 and 8115-2, generically referenced 8115. Thecircuit 600 further comprises an antenna 8120 of RFID type adapted tothe characteristics of the circuit 8105. Again, the antenna 8120 istypically a coil linked to the circuit 8105 via the two links AC0 andAC1.

Like for the circuit 8000, the RFID circuit 8105 is connected here tothe microcontroller 8010 by a bus of I2C type comprising the links SCLand SDA and the electrical supply terminal Vcc of the microcontroller8110, like that of the resonant circuits 8115-1 and 8115-2, is connectedto the Vout terminal of the RFID circuit 8105 delivering a voltage.

However, contrary to the circuit 8000, the synchronization signal of themicrocontroller, used to control the triggering or stopping of theresonance (enabling the location of the mobile entity) is connected hereto the Vout terminal of the RFID circuit 8105 delivering a voltage.

Moreover, the electrical supply terminal Vcc of the microcontroller8110, like that of the resonant circuits 8115-1 and 8115-2, is connectedto the terminal Vout of the RFID circuit 8105 delivering a voltage via adiode 8125. Furthermore, a resistor 8130, for example a resistor of onemega ohm (1 M′Ω) links the terminal Vout of the RFID circuit 8105 to areference terminal Vss.

Again, the RFID circuit 8105 is linked to the RFID antenna 8120 whichenables it to receive electrical energy from the RFID reader and todialog in reading/writing with the RFID reader to update its memory.Furthermore, as the output Vout of the RFID circuit 8105 is linked tothe supply Vcc of the microcontroller 8110 and of the resonant circuits8115-1 and 615-2, these three circuits are electrically supplied by theRFID circuit 8105.

The synchronization of the microcontroller 8110 is carried out here bythe output Vout of the RFID circuit 8105. Thus, when the RFID readerprovides energy to the mobile entity 8100, the output Vout from the RFIDcircuit 8105 provides a control voltage which is to be found at theinput Sync of the microcontroller 8110. This control voltage representsa first logic state. Conversely, when the output Vout passes to highimpedance when the RFID reader no longer supplies energy to the mobileentity 8100, the input state Sync of the microcontroller 8110 passes to0 Volts thanks to the resistor for pull-down to ground and thanks to thediode 8130 which prevents the return of current, representing a secondlogic state. The first and second logic states enable thesynchronization of the microcontroller 8110.

According to this embodiment, it is the software application running onthe RFID reader that has the task of generating a remote powering signaland of activating that signal when it is desired to synchronize themicrocontrollers of the mobile entities.

FIG. 8c illustrates a third variant of an electronic circuit 8200 of amobile entity. Like the circuit 8000, the circuit 8200 comprises astandard component 8205 providing functions of RFID type and integratinga dual-port memory (RFID component), a microcontroller 8210 and tworesonant circuits 8215-1 and 8215-2, generically referenced 8215. Thecircuit 8200 further comprises an antenna 8220 of RFID type adapted tothe characteristics of the circuit 8205. Again, the antenna 8220 istypically a coil linked to the circuit 8205 via the two links AC0 andAC1.

Like for the circuit 8000, the RFID circuit 8205 is connected here tothe microcontroller 8210 by a bus of I2C type comprising the links SCLand SDA and the electrical supply terminal Vcc of the microcontroller8210, like that of the resonant circuits 8215-1 and 8215-2, is connectedto the Vout terminal of the RFID circuit 8205 delivering a voltage.

However, contrary to the circuit 8000, the synchronization signal of themicrocontroller 8210 is not used. To be precise, the synchronization iscarried out here based on the result of an analog comparator of themicrocontroller 8210, of which the terminals are denoted C1 and C2. Asillustrated, these terminals are connected, respectively, to theterminals AC0 and AC1 of the RFID antenna 8220. Therefore, the controlof the triggering or stopping of the resonance (enabling the location ofthe mobile entity), is directly linked to the RFID antenna 8220 here.

Again, the RFID circuit 8205 is linked to the RFID antenna 8220 whichenables it to receive electrical energy from the RFID reader and todialog in reading/writing with the RFID reader to update its memory.Furthermore, as the output Vout of the RFID circuit 8205 is linked tothe supply Vcc of the microcontroller 8210 and of the resonant circuits8215-1 and 8215-2, these three circuits are electrically supplied by theRFID circuit 8205.

The analog comparator of the microcontroller 8210, linked to theterminals C1 and C2, is configured in counting mode (sensing mode). Thismakes it possible to obtain a count of the number of oscillations outputfrom the RFID antenna 8220. Thus, a frequency equal to the frequency ofthe carrier emitted by the RFID reader may be detected at the output ofthe analog comparator when the latter emits a carrier, for example afrequency equal to 15 MHz. If, on the contrary, the RFID reader emits nocarrier, no frequency is detected at the output of the analog comparator(or a frequency distinct from that of the carrier). In other words, thesynchronization of the microcontroller 8205 is carried out via thedetection or not of the RFID reader carrier. The software applicationrunning on the RFID reader thus has the task of generating the carrieror not, for example a carrier having a frequency equal to 15 MHz,synchronously with the activation frequency of the mobile entities.

It is observed here that to stop an RFID carrier practicallyinstantaneously, its resonant circuit is cut at the instant the currentpassing through it is zero.

FIG. 8d illustrates a fourth variant of an electronic circuit 8300 of amobile entity. Like the circuit 8000, the circuit 8300 comprises astandard component 8305 providing functions of RFID type and integratinga dual-port memory (RFID component), a microcontroller 8310 and tworesonant circuits 8315-1 and 8315-2, generically referenced 8315. Thecircuit 800 further comprises an antenna 8320 of RFID type adapted tothe characteristics of the circuit 8305. Again, the antenna 8320 istypically a coil linked to the circuit 8305 via the two links AC0 andAC1.

Like for the circuit 8000, the RFID circuit 8305 is connected here tothe microcontroller 8310 by a bus of I2C type comprising the links SCLand SDA and the electrical supply terminal Vcc of the microcontroller8310, like that of the resonant circuits 8315-1 and 8315-2, is connectedto the Vout terminal of the RFID circuit 805 delivering a voltage.

However, contrary to the circuit 8000, the synchronization signal of themicrocontroller 8310 is not used. To be precise, the synchronization iscarried out here based on the value of an item of data, typically onebit, stored in the dual-port memory of the RFID circuit 8305. Therefore,the control of the triggering or stopping of the resonance (enabling thelocation of the mobile entity), is directly linked to a value of theRFID circuit 8305 here.

Again, the RFID circuit 8305 is linked to the RFID antenna 8320 whichenables it to receive electrical energy from the RFID reader and todialog in reading/writing with the RFID reader to update its memory.Furthermore, as the output Vout of the RFID circuit 8305 is linked tothe supply Vcc of the microcontroller 8310 and of the resonant circuits8315-1 and 8315-2, these three circuits are electrically supplied by theRFID circuit 8305.

As indicated earlier, the synchronization of the microcontroller 8310 iscarried out via the reading, here on the I2C bus, of a synchronizationbit of which the change of state enables the synchronization to beactivated. Such a synchronization bit advantageously has a predeterminedaddress.

The software application running on the RFID reader has the task ofgenerating the change of state of the synchronization bit in the memoryof the RFID circuit 8305.

Each mobile entity here comprises at least one solenoid associated witha capacitor, in parallel, to form at least one resonant circuit havingthe task of emitting a location signal. This resonant circuit isstimulated here by a microcontroller embedded in the mobile entity.

According to an embodiment, the microcontroller situated in the mobileentity stimulates a resonant circuit by one of its outputs configured togenerate a pulse-width modulated cyclic signal at a frequency close tothe natural frequency of the resonant circuit. The control of the cyclicratio results in modulating the power emitted by the location module.

It is to be noted here that recent microcontrollers have circuitsenabling pulse width modulated signals to be generated. The use of thishardware functionality enables the microcontroller to freely executeinstructions of software code during the generation of the signal. Thus,the microcontroller can implement other functions and performcomputations without disturbing the timing of the pulse width modulatedsignal.

FIG. 8e illustrates an example of a resonant circuit for a mobileentity, controlled by a microcontroller.

The resonant circuit 8400 comprises an input terminal 8405 connected toa microcontroller to receive therefrom a pulse width modulated signal(referred to as a PWM signal). This terminal is connected, via aresistor R4, for example a resistor of 20 k′Ω, to the control terminalof a transistor Q1 used in switching mode. The input from the transistorQ1 is connected to an inductive circuit LC comprising an inductor L1 anda capacitor C1 mounted in parallel. The other branch of this inductivecircuit is connected to a resistor R1 connected to a voltage source, forexample a regulated voltage of 3.3V. The value of the resistor R1 isequal to 100′Ω here. The value of the inductor L1 is for example 220 ΩHwhile the value of the capacitor C1 is for example 3.2 nF. The outputfrom the transistor Q1 is connected to a resistor R2 which is moreoverconnected to ground. The value of the resistor R2 is for example equalto 100′Ω. A pull-down resistor R3 of which the value here is equal to 1MO connects the control terminal of the transistor Q1 to ground.

The starting and stopping phases of the oscillations are periods of timein which the location signal received by a detection surface is not ingeneral exploitable since it is generally not powerful enough and of anamplitude that is not constant and not controlled. In a utilization inwhich very many mobile entities are to emit in turn, these starting andstopping times become non negligible relative to the useful emissiontime during which the electronics of the detection surface is actuallyable to locate the mobile entities.

Therefore, it is important that the starting and stopping phases beshort. For this purpose, on starting, at the time of the firstoscillations, the cyclic ratio of the digital signal generated by themicrocontroller of the mobile entity is modified to add more power andvery rapidly attain the nominal amplitude, preferably in only one or twocycles.

In the same way, during the stopping phase, rather than simply stoppingto stimulate the resonant circuit and allowing it to relax at anexponential rate (RLC equivalent circuit), for one or two cycles, themicrocontroller adds to each cycle a pulse out of phase with the naturaloscillation of the circuit.

FIG. 8g represents a simulation showing the active control of thestarting and stopping phases of the oscillation of an inductor. The timeis represented along the x-axis. The signal in continuous linerepresents the voltage at the terminals of the inductive circuit LC, thesignal in dotted lines represents the voltage control pulses from themicrocontroller and the signal in bold dotted lines of variable lengthrepresents the supply current consumed by the resonant circuit.

It is observed here that the modulation of the power emitted by theresonant circuits of the location modules makes it possible to encode abitstream corresponding to data to transfer to a computer system linkedto the location surface. Knowing the amplitude A1 corresponding to thelow state and the amplitude A2 corresponding to the high state of alocation signal, it is possible to use an NRZ type modulation (NRZstanding for Non Return to Zero) which enables the detection surface todiscriminate the amplitude variations associated with a data transfer,from those which are due to all the causes which may produce arelatively slow variation in the received power (comprising inparticular the variation in the distance between the mobile entity andthe detection surface as well as the variation in the supply voltage ofthe mobile entity).

It is also observed that when a mobile entity acquires energy (afunction termed energy harvesting) on an RFID carrier, the currentsinduced in the receiver coil of the mobile entity produce a negativecounter-reaction which locally reduces the power of the magnetic field.In the phases in which a mobile entity does not need more energy thanthat which has already accumulated, it may, preferably, open the circuitof its receiver coil to thereby eliminate the perturbation induced inthe local magnetic field. Such a function may in particular be producedusing a MOSFET type analog switch (MOSFET being an acronym for MetalOxide Semiconductor Field Effect Transistor) of low resistance andleakage current.

Moreover, whatever the hardware solution envisioned for thecommunications, the data transfers to and from the mobile entities maybe encrypted according to an encryption system, for example anencryption system based on public and private keys of RSA type (RSAstanding for Rivest Shamir Adleman) or AES type (AES standing forAdvanced Encryption Standard).

It is observed here that the activation of resonant circuits enablingtheir location may be carried out by the microcontrollers of the mobileentities, these latter receiving synchronization information from anRFID type signal received from the mobile entity considered. However,this information typically derives from a low frequency signal, forexample a signal having a frequency of 1 Hz (such a frequency may beobtained when the synchronization is made by rupture of the remotepowering carrier since it is desirable to limit the cut-off frequency).

However, the microcontrollers used must generate pulses in order totrigger each solenoid in a refresh cycle, that is to say a cycle fordetermining the position and, where appropriate, the orientation of eachmobile entity of a set of mobile entities, compatible with a real-timeuse of the system. Such a refresh frequency is, for example, 60 Hz. Atthis frequency, each refresh cycle has a period of 16 ms. Pulses musttherefore be supplied by each microcontroller every 16 ms, with atemporal offset for the start of each pulse, for each resonant circuit,which depends on a timeslot attributed to the latter. The attribution ofsuch a timeslot may be carried out in accordance with the teaching ofpatent application WO 2012/028827.

As each microcontroller receives only one low frequency informationitem, it must have a time base which is specific to itself to generatepulses every 16 ms and adjust that time base as soon as there is anexternal synchronization signal available. This makes it possible toavoid too great a drift of the internal clock of the microcontroller.

In the situation in which the internal clocks of the mobile entities andthe electronics of the location surface do not have exactly the samecadence, the mobile entities compensate for their internal clock basedon a comparison of the time measured between two consecutive items ofsynchronization information with a predetermined theoretical time. It isobserved that the longer that time, the more accurate is thatcorrection. Thus, if the measurement of the time is made with anaccuracy P and over a predetermined theoretical time D, the accuracy ofthe clock compensation of the microcontroller is equal to P/D. By way ofillustration, if the accuracy is P=10 μs and the time is D=1 s, theaccuracy obtained is equal to 1 e-5, i.e. potentially a thousand timesbetter than the +/−2e-2 typical of an internal non-calibrated clock of amicrocontroller.

The location modules may also receive energy from radiating rows andcolumns of a location surface, in particular from the rows and columnsused to receive location signals from location modules.

FIG. 8f illustrates an example of a location module making it possibleto receive energy from rows and columns of a location surface, that areused to receive location signals from location modules. As illustrated,the location module 8500 is provided here with a switch 8505 enablingthe radiation from a solenoid 8510 according to a conventionalconfiguration used for its location. In this configuration, amicrocontroller 8515 generates a signal, for example a period signalhaving a frequency of 200 KHz, according to a synchronization commandfrom a synchronization module 8520. The signal generated is amplified ina resonant circuit 8525 and sent to the solenoid 8510.

The switch 8505 also enables the solenoid 8510 to be used as an energyreceiver by inductive coupling, the solenoid 8510 being, for suchpurposes, connected to an energy harvesting circuit 8530. By way ofillustration, such an energy harvesting circuit may comprise rectifyingdiodes and a capacitor enabling current to be stored in order to begiven back later.

The switch 8505 lastly enables one of the two terminals of the solenoid8510 to be left open such that no current can pass through it. Thisembodiment is in particular useful in phases during which a mobileentity has no need for more energy than that which has already beenstocked, and it thus eliminates the perturbation induced in the localmagnetic field. This non-captured energy thus becomes available formobile entities that are close.

The synchronization information is provided by the synchronizationmodule 8520 which may, for example, be an FM radio receiver, inparticular an FM receiver capable of receiving signals having afrequency around 433 MHz. An item of synchronization information must beused to indicate to the microcontroller whether it is to be in location,energy acquisition or “open” mode. This information may be sent in theform of a bitstream by a microcontroller of the location surface.

It is noted here that the RFID protocol uses a HF (High Frequency)carrier which, if continuously emitted, may perturb the process forlocation of the mobile entities by the location surface. In order toeliminate or at the very least reduce this effect, the RFID carrier is,according to a particular embodiment, continuously emitted with afrequency of approximately 13.56 MHz. Moreover, the implementation ofone or more low-pass filters at the input of the detection surface makesit possible to reject that frequency while allowing the signal from thelocation modules to pass.

According to other embodiments, the RFID carrier is only emitted for oneor more timeslots of each refresh cycle, the location modules of themobile entities being activated outside those timeslots, without risk ofperturbation.

Furthermore, in order to reduce its electrical consumption, a mobileentity may place its electronics on standby for the timeslot of eachrefresh cycle (fixed and repeating), during which it must not activateits location module or send data.

According to a particular embodiment, certain mobile entities do notactivate their location modules at each refresh cycle, here denoted T1,but according to a multiple, denoted N, of that cycle, that is to sayaccording to a cycle N×T1. Such an embodiment is in particular adaptedto mobile entities intended to be rarely moved on the location surface.This results in enabling the electrical consumption of those mobileentities to be reduced, which may, in synchronized regime, place theirelectricity consuming components on standby, including those in chargeof the reception of a synchronization signal, during a time slot atleast equal to (N−1)×T1. The electrical consumption reduction factor isthen of the order of N.

Still according to a particular embodiment, the common synchronizationsignal may comprise at least two distinct signals here denoted SyncA andSyncB, which can be differentiated between by the mobile entities By wayof illustration, the signal SyncA is emitted according to a cycle of Ncycles of duration T1 whereas the signal SyncB is emitted at each cycleof duration T1. Thus, when a delay index equal to M, with 0<M<N, isattributed to a mobile entity, the latter is activated every N cycles,at a time M×T1 following the reception of the signal SyncA.

It is noted here that, although in theory, a mobile entity only requiresthe signal SyncA, in practice the use of the signal SyncB is preferable,when the value of M is non-zero, to increase the accuracy of sequencingof the mobile entities.

Thus, for example, with reference to FIG. 8h , concerning the module 3(activated when M=2) and a timeslot equal to three, the module waits, oninitialization, for the reception of the signal SyncA then enters astate of standby for a time less than 2×T1. At the end of standby, itawaits the signal SyncB then waits for a time equal to three timeslotsto activate an electromagnetic emission (that is to say, typically, toexcite a solenoid). It then returns to a state of standby until a timepreceding the reception of the signal SyncB of the following cycle N×T1.As from that time, it is, in theory, no longer necessary for the mobileentity to await the signal SyncA. However, to eliminate potentialproblems of desynchronization, the mobile entity may advantageouslyverify from time to time, for example once per second, that thereception of the signal SyncA is indeed situated at the time provided inits cycle N×T1. If a drift is observed, the mobile entity preferablyperforms the full synchronization cycle again as of the reception of thesignal SyncA.

The synchronization signals are, for example, sent by frequencymodulation of a radio carrier. By way of illustration, the signals SyncAand SyncB are square pulse signals of different direction.

FIG. 8h represents a timing diagram of synchronization when twosynchronization signals SyncA and SyncB are used. The signal SyncA isemitted here according to a cycle of N cycles of duration T1 whereas thesignal SyncB is emitted at each cycle of duration T1, with T1=25 ms andN=4. The signal SyncA has square pulses of one millisecond durationwhereas the signal SyncB has square pulses of one and a halfmilliseconds length.

The timing diagram represented concerns the activation of four mobileentities each comprising a location module. These mobile entities hereshare the same timeslot and have delay indices M equal to 0, 1, 2 and 3,respectively.

Still According to a particular embodiment, the location surface as wellas each of the mobile entities comprise an electronic system capable ofimplementing the functionality known under the name of MultiCeiver ofthe protocol known under the name Enhanced Shockburst (MultiCeiver andEnhanced Shockburst are trademarks), this functionality making itpossible to produce the common synchronization signal.

This functionality may in particular be implemented using the electroniccomponent having the reference nRF24LE1 from Nordic Semiconductor. Inaccordance with this embodiment, the circuit nRF24LE1 of the locationsurface emits the synchronization signals SyncA and SyncB in thefollowing manner:

-   -   each of the mobile entities reserves a logic address ALSYNC of        predetermined value and which is identical for all the mobile        entities, that address here is reserved in a communication        interface called “data pipe 0”;    -   the circuit nRF24LE1 of the location surface sends to the        address ALSYNC, at each refresh cycle T1, a data packet        comprising at least one byte. For the synchronization signal        SyncA, the first byte of the data packet has a first        predetermined value and, for the synchronization signal SyncB,        the first byte of the data packet has a second value, distinct        from the first value used for the synchronization SyncA;    -   at the mobile entities, the reception of each of these signals        produces, with a constant time period, a hardware interrupt        which indicates the precise time for the synchronization.        Furthermore, by reading the first byte of the received data        packet, the software of the nRF24LE1 circuit determines whether        it is the synchronization signal SyncA or SyncB.

By way of illustration, the location modules may be integrated intomobile devices such as robots or toys, for example cars or helicopters.The acquisition in real time of the position and orientation of a mobiledevice as well as the control of actuators thereof make it possible tosteer it automatically, for example for it to follow particular pathswhich may in particular be defined by a software application. For suchpurposes, the software application used and which runs on a computer,for example a PC (PC standing for Personal Computer), a smartphone ortablet, may send control commands via an interface of SDK type (SDKstanding for Software Development Kit). Such control commands are, forexample, a direction and speed of rotation of the motors. They are codedand sent to the RFID type reader used which may then send them in theform of an RFID signal, in a write instruction, to an RFID type circuitof a location module.

A microcontroller thereof may then read them from the memory of the RFIDtype circuit using, for example, an I2C bus. These commands or datarepresenting those commands are, preferably stored in memory atpredetermined locations of the RFID type circuit. The microcontroller ofthe location module is here provided with outputs, for example PWM typeoutputs, enabling actuators such as motors to be controlled based oninformation stored in memory in the RFID type circuit.

Naturally, to satisfy specific needs, a person competent in the field ofthe invention will be able to apply modifications to the precedingdescription. In particular, although the invention may, for the purposesof illustration, be described, in particular, with reference to the RFIDprotocol, the invention is not limited to the implementation thereof.

Activation and Location of the Mobile Entities

As described above the location modules to be activated may beidentified in analog or digital manner. The analog identification of alocation module may be carried out by sending a dedicated frequency, inaccordance with several modes, in particular in accordance with aspecific carrier frequency for each location module (that frequencyidentifies the location module which is activated). The embeddedelectronics thus reacts to the specific carrier which corresponds to it.Alternatively, a single carrier frequency may be used for all thelocation modules. This frequency modulates a useful signal which isreceived by each location module. It is the value of the modulatedfrequency of that useful signal that enables the identification of thelocation module to detect. The activation frequencies of each locationmodule are, for example, defined in the factory at the time of theirassembly and are configured in terms of software in the control modulefor position sensing and detection.

The digital identification of a location module is carried out by thesending of a code, typically over several bits, in an activationmessage. This identification mechanism enables great flexibility of usesince it enables the programming (and thus the modification) of theidentification of each location module.

FIG. 9 illustrate a first example of an algorithm capable of being usedto sequentially activate a set of location modules and to compute thepositions and/or orientations of the corresponding mobile devices.

A first step consists here of initializing a variable i, representing anindex to location modules, to the value zero (step 900). In a followingstep (step 905), the value of the variable i is compared with the valueof a constant M representing the number of location modules supported bythe system. Typically, the order of magnitude of the constant M is onehundred. If the value of the variable i is greater than or equal to thatof the constant M, the variable i is reinitialized (step 900).

If, on the contrary, the value of the variable i is less than that ofthe constant M, a test is carried out to determine whether the locationmodule having the index i has been used (step 910), that is to saywhether the location module having the index i is valid. The validity ofthe location modules may be stored in memory in a table which may beupdated by an application using the interface formed by the mobiledevices comprising those location modules and the location system ofthose modules. As illustrated by the use of dashed line, this step isoptional.

If the location module corresponding to the index i is valid, thatmodule is activated (step 915). As described above, the activation ofthe location module having the index i consists, for example, ofemitting a signal of which the carrier has a frequency characterizing anidentifier of that location module.

When the location module having the index i is activated, it emits anelectromagnetic field enabling its location by measurement of voltagesinduced in loops of the detection surface as indicated earlier.

The control module for position sensing and detection is then able tocompute the position of the activated location module (step 920).

These items of information are stored in memory to be exploited by thecomputing module (step 925). They may in particular be stored in memoryin a location module position table based on which can be estimated thepositions and/or orientations of the mobile devices comprising thelocation modules.

The variable i is then incremented by one (step 930) and the precedingsteps are repeated (steps 905 to 930) until the positions of all thelocation modules (or valid location modules) have been determined.

Similarly, if the location module corresponding to the index i is notvalid (step 910), the variable i is incremented by one (step 930) andthe preceding steps are repeated (steps 905 to 930) until the positionsof all the location modules (or valid location modules) have beendetermined.

The position and/or the orientation of each mobile device are computedbased on positions of the location modules. This computation may becarried out when the positions of all the valid location modules havebeen computed or, mobile device by mobile device, when the positions ofall the valid location mobile device belonging to the same mobile devicehave been computed.

It is noted here that the validity of location modules may in particularby linked to the logic of the application using the interface formed bythe mobile devices comprising those location modules and the locationsystem of those modules. By way of illustration, in the case of a game,the non-valid location modules may correspond to mobile devicesrepresenting pawns not used in the game, for example pieces having beentaken in a game of chess or pawns not used in a given game scenario.

FIG. 10 illustrate a second example of an algorithm capable of beingused to sequentially activate a set of location modules and to computethe positions and/or orientations of the corresponding mobile devices.

This algorithm makes it possible in particular to manage the fact thatcertain mobile devices may leave the zone of movement (that is to sayhere the detection surface) and that the positions and/or orientationsof the corresponding mobile devices no longer require to be estimated. Asecondary software loop however monitors their possible re-inclusion onthe detection surface and the ensuing need to again estimate theirpositions and/or orientations. This algorithm makes it possible, incomparison with the algorithm described with reference to FIG. 9, toreduce the overall duration of the sequence for activation of all thelocation modules by dynamically managing their validity.

In this algorithm, the constant M corresponds to the maximum number oflocation modules supported by the system, the variable i characterizesthe index of a location module, the table P corresponds to the table ofpositions of the location modules, the table V corresponds to the tableof validity of the location modules, the variable C is an overallvariable corresponding to the total number of location modules used, Kis a predetermined constant corresponding to the maximum number ofiterations of searching for location modules outside the detectionsurface (a typical value for K is of the order of ten) and A is avariable representing a count-down index of the iterations of searchingfor the location modules situated outside the detection surface for anoverall cycle.

A first step is directed to initializing the variables i and C to zero(step 1000). In a following step the value of the variable i is comparedto that of the constant M (step 1002). If the value of the variable i isless than that of the constant M, the location module validity table isupdated such that the location module corresponding to the index i isconsidered as valid (step 1004). The variable i is then incremented byone (step 1006) and the new value of the variable i is compared to thatof the constant M (step 1002). Steps 1002 to 1006 enable the locationmodule validity table to be initialized.

If, on the contrary, the value of the variable i is greater than orequal to that of the constant M, the variable i is reinitialized to zero(step 1008). In a following step the value of the variable i is againcompared to that of the constant M (step 1010). If the value of thevariable i is less than that of the constant M, a test is carried out todetermine whether the location module corresponding to the index i isvalid (step 1012).

If the location module corresponding to the index i is valid, thatmodule is activated (step 1014) such that it emits an electromagneticfield enabling its location by measurement of voltages induced in loopsof the detection surface.

The control module for position sensing and detection is then able tocompute the position, and, where required, the orientation, of theactivated location module (step 1016).

A test is then carried out on the coordinates obtained from the locationmodule (step 1018). If those coordinates are zero, the location modulevalidity table is updated such that the location module corresponding tothe index i is considered as not valid (step 1020). In the oppositecase, if those coordinates are not zero, those coordinates are stored inmemory to be exploited by the computing module (step 1022). They may inparticular be stored in memory in the location module position tablebased on which can be estimated the positions and/or orientations of themobile devices comprising those location modules, as describedpreviously.

The variable i is then incremented by one (step 1024) and its value isagain compared to that of the constant M (step 1010).

Similarly, if the location module corresponding to the index i is notvalid (step 1012), the variable is incremented by one (step 1024) andits value is again compared with that of the constant M (step 1010).

If the value of the variable i is greater than or equal to that of theconstant M (step 1010), the value of the variable A is initialized tothe value zero (step 1026). A test is then carried out to compare thevalue of the variable A with that of the constant K (step 1028). If thevalue of the constant K is less than or equal to that of the variable A,the value of the variable i is reinitialized to zero (step 1008) and thesteps described previously are repeated.

In the opposite case, a test is carried out to determine whether thelocation module corresponding to an index of which the value is equal toC is not valid (step 1030).

In the affirmative, that module is activated (step 1032) such that itemits an electromagnetic field enabling its location, for example bymeasurement of voltages induced in loops of the detection surface.

The control module for position sensing and detection is then able tocompute the position of the activated location module (step 1034).

A test is then carried out on the coordinates obtained from the locationmodule (step 1036). If those coordinates are zero, the location modulevalidity table is updated such that the location module corresponding tothe index of which the value is equal to that of the variable C isconsidered as not valid (step 1038). In the opposite case, the locationmodule validity table is updated such that the location modulecorresponding to the index of which the value is equal to that of thevariable C is considered as valid (step 1040).

The values of the variables A and C are then incremented by one (step1042). Similarly, if the location module corresponding to an index ofwhich the value is equal to that of the variable C is not valid (step1030), the values of the variables A and C are then incremented by one(step 1042).

A test is then carried out to compare the value of the variable C withthat of the constant M (step 1044). If the value of the variable C isless than that of the constant M, the values of the variable A and ofthe constant K are compared (step 1028) and the steps describedpreviously are repeated.

If the value of the variable C is greater than or equal to that of theconstant M, the value of the variable C is reinitialized to the valuezero (step 1046). The values of the variable A and of the constant K arethen compared (step 1028) and the steps described previously arerepeated.

Control of the Host Device

Returning to the context of FIG. 5, is assumed that at least one mobiledevice is disposed on a host device or in the vicinity thereof. Themobile device may be placed on an upper surface of the host device (orinteracting surface) or be located in the vicinity of thereof. It isconsidered that the mobile device is in the vicinity of the host deviceor in the vicinity of an upper surface thereof when the mobile device isclose enough to the detection layer of the host device for it to bepossible to detect the magnetic field emitted by the mobile device (ormore specifically emitted by a location module thereof).

A user manipulates the mobile device and imparts to it a movementrelative to the upper surface of the host device. According to themovement of the mobile device, the host device determines a command toexecute.

To that end, for each mobile device in the vicinity of the host device,the latter stores, in a sliding history, positions of their locationmodule or modules. For example, such position comprises the x-coordinateand the y-coordinate of the mobile device relative to the interactingsurface. These are for example defined according to the impact points ofthe electromagnetic field on the detection surface. The position mayfurther comprise the distance between the mobile device and theinteracting surface (that is to say) its altitude. The latter may bedefined according to variations in the electromagnetic power measured.

When the host device has available the movement history of the mobiledevice in the history record over a temporal window (for example of theorder of one second), it is possible to compare the form of the momentto a reference movement diagram (or model) to be recognized. Eachmovement diagram is associated with a reference movement (that is to saya gesture made by the user with the mobile device).

FIG. 11a illustrates a click movement. In this movement, the userrapidly lifts and replaces the mobile device relative to the hoststation. The host station then detects a rapid variation in altitude inone direction then in the other (moving away of the host station thenmoving back). For example, this variation is made within a time of theorder of half a second or less. FIG. 11a is a graph presenting thereference movement diagram associated with the click movement, showingthe change in altitude of the mobile device relative to the host stationover time.

FIG. 11b illustrates a back-and-forth movement. In this movement, theuser rapidly moves the mobile device away from an initial position thenback while remaining in the same plane of the interacting surface forinteraction with the host device. FIG. 11b is a graph presenting thereference movement diagram associated with the back-and-forth movement,showing the change in distance, in a plane parallel to the interactingsurface of the host device, between the position of the mobile deviceand an initial position.

FIG. 11c illustrates a shake movement. In this movement, the user makesseveral successive back-and-forth movements with the mobile device. FIG.11c is a graph presenting the reference movement diagram associated withthe shake movement, showing the change in distance, in a plane parallelto the interacting surface of the host device, between the position ofthe mobile device and an initial position.

FIG. 11d illustrates a slide movement. In this movement, the user makesthe mobile device perform a rectilinear displacement in a plane parallelto the interacting plane of the host device. FIG. 11d is a graphpresenting the reference movement diagram associated with the slidemovement, showing the change in distance covered by the mobile device ina plane parallel to the interacting surface of the host device.

Some mobile devices may comprise a plurality of location modules, forexample containing solenoids, to generate inductor magnetic fields. Itis thus possible to determine for these mobile devices, theirorientation according to an axis orthogonal to the interacting surfaceof the host device. A rotational movement imparted by a user to a mobiledevice may thus be detected by the host device.

When one or more of the movements referred to above, or others, isdetected, it is associated with a command of the host device.

For example, the click may make it possible to activate a predefinedaction or to validate a choice from a menu displayed to the user.

The shake may for example enable an action in course to be cancelled oractivated (that is to say to perform an “undo” type operation typicallypresent in computer applications).

According to still another example, the slide may enable a selection tobe made or to vary a slider value.

The rotation may for example enable a selection to be made from aplurality of contextual items displayed to a user or to vary a curvingslider value (in the manner of a potentiometer).

Movements may be combined to give interfaces of a new type, based on theexclusive use of objects and without requiring the use of an associatedtouch screen or a keyboard and mouse. Such objects may however be usedas a complement.

Examples of implementation of commands of the host device are describedbelow with reference to FIGS. 12a to 12 g.

As illustrated in FIG. 12a , a mobile device 1200 is on a screen 1201itself superposed over a host device 1203. The screen may form part ofthe host device. Alternatively, the mobile device may be disposed overthe host device and the screen may be remotely located, that is to saynot integrated into the host device.

When a user performs a click with the mobile device by raising thedevice upward (arrow 1204) then putting it down again (arrow 1205), thehost device detects it and executes a command associated with thatmovement.

This is for example the display of a menu 1206 as illustrated by FIG.12b . This menu displays for example around the position of the pawn.According to a further example, this menu comprises contextual items1207, 1208, 1209 such as icons or text.

Alternatively or in combination, the execution of the command associatedwith the movement is not accompanied by a display, but is accompanied bya triggering of a sound or of a light-emitting item associated with thecommand. The light-emitting item may be disposed at the location of theinteracting surface or on the remote device.

To select a contextual item, it is for example possible to perform aslide movement, as illustrated in FIG. 12c . For example, the userdisplaces the mobile device towards item 1207 (arrow 1210). In order toprovide visual feedback to the user, the item 1207 may for example bedisplayed as sinking into a slot, as though pushed by the pawn (arrow1211).

FIG. 12d illustrates the selection of a contextual item by means of aclick and a rotation. The mobile device is located for example orientedtowards the contextual item 1207. This item is then highlighted. Next,as illustrated by FIG. 12e , the user imparts a rotational movement tothe mobile device around an axis orthogonal to the screen 1200 (arrow1212) towards another contextual item, for example the item 1208. Thisitem is then highlighted and the item 1207 returns to its initialappearance (no highlight).

To validate the selection of the item 1208 and to trigger the associatedaction or command, the user may then perform a click movement.

Alternatively, the validation may be carried out passively by leavingthe mobile device motionless for several seconds after having selectedthe contextual item, without requirement to combine with a clickmovement.

With reference to FIG. 12f , a description is given of carrying out theshake movement to activate an action cancellation command. Thiscancellation enables a change of mind over an action undertaken by theuser in order to return to the state the host device was in prior to theuser's action. For example, the user imparts a back-and-forth or shakemovement to the mobile device (arrow 1213). The system then returns tothe state prior to the activation of the cancellation action.

The forms of use of movements (or gestures) imparted to the mobiledevices are not limited to those presented above. It is possible toprovides other ones. Furthermore, the combinations of movementspresented are not limiting, it is possible to modify them or provideother ones. Furthermore, the associations between the movements and thecommands (or actions) presented above are not limiting.

In particular, the activation of an action may be carried out bydetection of a single click movement without combination with othergestures. This is for example the case when the action associated with amobile device is unique and does not therefore justify a choice betweenseveral options. The click movement may immediately trigger the uniqueaction associated with the mobile device.

With reference to FIG. 12g , a movement will be described enabling anaction to be cancelled or to restore an action. When the user hastriggered an action by a movement of the mobile device, he may cancel itby performing a semi-circle leftward (arrow 1214) with the mobiledevice. The triggered action is then cancelled. If after havingcancelled that action, the user wishes to restore it, that is to say tocancel the cancellation, he can perform a semi-circle rightward (arrow1215) with the mobile device.

FIG. 13 is a flowchart of steps implemented within the host deviceaccording to embodiments;

In a first step 1300, the current position of a mobile device isdetermined. This may be its distance relative to the interacting surfaceof the host device, and/or its coordinates in a frame of referenceassociated with that surface and/or an orientation of the mobile deviceaccording to an axis orthogonal to that surface. Step 1300 may betriggered by the reception of an activation signal from the mobiledevice.

Once the position has been detected, it is recorded at a step 1301 in ahistory of the positions of the mobile device. This history concerns asliding temporal window, that is to say that the history comprises thelast positions detected over a given period of time, for example a fewseconds, and that each new position erases the oldest position.

The history of the positions makes it possible at every instant tocompare, at a step 1302, the change in these positions, that is to saythe movement of the mobile device, to reference movements as discussedabove (click, back-and-forth, shake, rotation or other movements).

If it is determined at a step 1303 that the movement of the mobiledevice does not correspond to a reference movement (NO), the processreturns to step 1300. Otherwise (YES), a command (or action) associatedwith that reference movement is triggered at a step 1304.

According to embodiments, a neural network system is used to recognizethe reference movements. For example, the reference movements areidentified by the system by learning based on movements of the mobiledevice. During this learning a state, or a signature, of the neuralnetwork may be identified by the system which associates it with areference movement. Subsequently, when that movement is repeated, itagain places the neural network in the same state which enables it torecognize the reference movement.

In this type of embodiment, comparison position by position is notcarried out between those of the reference movement to recognize andthose of the movement which has just been carried out and stored in thehistory. It is rather a matter of comparing a current state of theneural network (or signature) with a reference state (or signature).

Mobile Devices with an Interface

The mobile devices may comprise one or more user interfaces enabling thesending of signals to the host device to be triggered.

For example, a microcontroller in the mobile device makes it possible tomanage the location modules (containing for example oscillators linkedto solenoids) and to have several digital inputs which it is possible tolink to one or more types of switch disposed on the mobile device: apush button, a slider, a wheel or other switch.

The microcontroller may moreover code information sent to the hostdevice via communication protocols such as already described above, forexample the RFID protocol.

However, other modes of communication may be envisioned.

For example, it is possible to exploit “capacitive sensing” technologywhich enables such interfaces (push buttons, slides, wheels or otherinterfaces) to be implemented by a touch zone at the surface of themobile device or very close to the surface which makes it possible toreact to the touch of the user's skin. This technology may be managed bymicrocontroller and has the advantage of providing a non-mechanicalwear-resistant solution.

According to a further example, the microcontroller sends information tothe host device by varying the activation time of the solenoid which itcomprises. For example, when the interface of the mobile device is notput into action, that activation time has a different duration from thatwhich it has when the interface is in action. Thus, for example, if themobile device has a push button, and that button is pushed in, theactivation time of the solenoid is different from that when the pushbutton is not activated. By way of illustration, the activation time maypass from 1 ms to 1.5 ms when the interface is put into action.

According to another example, the microcontroller sends a PWM signal(PWM standing for Pulse Width Modulation) to a radiating amplifier tochange the emission frequency of the mobile device solenoid. By way ofillustration, the activation time may pass from 200 kHz to 210 kHz whenthe interface is put into action.

Other examples are possible, such as the sending of a binary frame bymodulating the signal emitted by the solenoid.

FIG. 14a illustrates a mobile device 1400 comprising a push button 1401,for example disposed at the vertex of the mobile device. For example,when the push button is operated, a signal is sent by the mobile deviceto the host station to trigger a position detection.

According to a further example, when the push button is operated, asignal is sent, by the mobile device to the host station, which themobile device assimilates to click movement. The push button then servesas an alternative interface or complementary interface.

The push button is for example managed by a microcontroller 1402 alsogiven the task of managing location modules with resonant circuits 1403,1404 (solenoids or other circuits).

FIG. 14b illustrates a mobile device 1405 comprising a slide or a wheel1406, for example disposed on a side face of the mobile device. Forexample, when the slide is operated, a signal representing the positionof the slide in its travel (arrow 1407) is sent by the mobile device tothe host station.

The slide may serve as an alternative interface or complementaryinterface. The commands associated with the slide may for example be a“zoom in/zoom out”, forward/backward translation of the image, or othercommand. The slide or the wheel may enable information coded between aminimum and a maximum to be sent to the host device. It is then possibleto associate a specific command with that variation in value.

The slide is for example managed by a microcontroller 1408 also giventhe task of managing location modules with resonant circuits 1409, 14010(solenoids or other circuits).

FIG. 14c illustrates a mobile device 1411 comprising a main body 1412and a secondary body 1413. The main body comprises a location module1414 (for example with a solenoid) and the secondary body comprises alocation module 1415 (for example with a solenoid). The main bodycomprises for example a microcontroller 1416 to control the locationmodules.

The secondary body is movable relative to the main body. Thus, thedistance d (arrow 1417) separating the location modules 1414 and 1415 isvariable. For example, a user may take the main body between her fingersand move the secondary body with her thumb.

The relative disposition of the two location modules for example makesit possible to provide a rotation detection function.

It is then possible to perform relative movements of the locationmodules, for example by way of alternative interface or complementaryinterface for the rotation movements.

EXAMPLES OF APPLICATIONS

According to the intended application, it may be necessary to limit theexploitation of the system (comprising a host device and at least onemobile device) to a subset of available location modules or to associatea particular function with certain location modules. Thus, in aninitialization phase of the system, it may be necessary to define a listof location modules of which the position is not to be computed (theirelectromagnetic emission is not activated by the activation module).This list may vary over time and may differ from its initial valuedefined at the time of the initialization phase. It is also possible, inan initialization phase, to attribute a specific role or function to alocation module or to a mobile device. Thus, for example, a mobiledevice associated with a predefined location module may play the role ofa King if that mobile device is exploited in a chess game program, thatsame mobile device may also play the role of an eraser or a felt-tip penin a drawing application or for instance have the role of a car in aroad-use education program.

By way of example, the association between location modules and afunction may be made by disposing the mobile devices comprising thoselocation modules on specific parts of the detection surface andtriggering a recording. The control module for position sensing anddetection then performs a complete activation sequence and the roles areassociated according to the respective positions of the mobile devices(for example pieces from a team A versus pieces from a team B).

When a screen is superposed on the detection surface, it is possible tochoose a role from a context menu for each mobile device by displaying amenu, near the position of each mobile device, proposing the differentpossible roles.

A particular application of the invention concerns board games byenabling the agreeable aspect of the board games and the pleasure ofmanipulating actual pawns or figurines to be maintained while profitingfrom the interactivity and dynamism of video games. In this field ofapplication, a large touch screen is, preferably, superposed on thedetection surface for the pieces.

The location modules are advantageously placed in bases of the figurinesused in the game so ensuring the detection of the position of thefigurines in the game.

The touch screen may display the game track on which the figurines willmove, so giving a dynamic visual medium. Typically, the screen displaysthe environment in animated and realistic form in which the figurinesare immersed (colors in a space ship for a science fiction game,geographical regions for a “risk” type game, a chess board if thefigurines are chess pieces, etc.).

On starting a game, the system proposes an attribution of functions tothe mobile devices in order to enable the program to produce a relationbetween the identifier of one or more detection modules and the figurinerepresented by that mobile device. This may be carried out by displayinga specific menu for role selection on the screen near the position ofeach figurine disposed on the board.

When the pieces have been recorded, that is to say that their roles havebeen assigned to them, they become veritable game interfaces. The systemcan then continuously verify that the movements of the figurines doindeed respect the limits of movement required by the rules of the gameby taking into account their role in the game (move from square tosquare in a corridor for example, comply with the appropriate movementsfor a game of chess, etc.). The system can also compute and display onthe screen the lines of sight between two figurines in a game of combator automatically compute and display the possible takes in chess. It isalso possible to trigger contextual visual animations under a figurineor based on a figurine. Thus selecting the shooting of a weapon from themenu of a figurine may make a specific flash appear around the shooterand the display of tracer bullets between two figurines. In similarmanner, it is possible to trigger contextual audio animations when therelative position of two figurines so enables. For example, on movementof a figurine, the system determines the existence of a line of sightwith another figurine, an audio alarm “target in view” may be triggeredby the system.

Similarly, it is possible to display context menus depending on theposition of the figurines (a menu for calculating the result of a handto hand combat displays if two enemy figurines are at a minimumdistance), give an automatic on-line help when a player makes aprohibited move with its figurine and modify the display on the screenwhen the players perform rotations with the figurines.

As described above, the figurines may be used as an interface tonavigate in the menu thanks to click, back-and-forth, slide or othermovements.

To meet specific needs, a person competent in the field of the inventionwill be able to apply modifications to the preceding description.

A computer program for the implementation of a method according to anembodiment of the invention may be produced by the person skilled in theart on reading the flow chart of FIG. 13 and the present detaileddescription.

Of course, the present invention is not limited to the describedembodiments, other variants and combinations of features are possible.

The present invention has been described and illustrated in the presentdetailed description with reference to the appended Figures. However thepresent invention is not limited to the embodiments presented. Othervariants and embodiments may be deduced and implemented by the personskilled in the art on reading the present description and appendedFigures.

In the claims, the term “comprise” does not exclude other elements orother steps. The indefinite article “a” does not exclude the plural. Asingle processor or several other units may be used to implement theinvention. The different features presented and/or claimed mayadvantageously be combined. Their presence in the description or indifferent dependent claims, does not indeed exclude the possibility ofcombining them. The reference signs are not to be understood as limitingthe scope of the invention.

The invention claimed is:
 1. A method of controlling a host device forat least one mobile device, the method comprising steps of: a firstdetermining step of determining (1300) a current position of said atleast one mobile device relative to an interacting surface of the hostdevice by at least one inductor magnetic field inducing at least oneelectrical signal in at least one electrical circuit (115) of the hostdevice; saving (1301) said current position in a position history file,said position history file comprising a set of positions including oneor more previous positions of said at least one mobile device over asliding temporal window, said position history file being stored in amemory device; comparing (1302) a form of an actual movement of said atleast one mobile device relative to the interacting surface of the hostdevice determined utilizing said current position and at least one ofsaid previous positions of said set of previous positions from saidposition history file with at least one reference movement diagram, saidat least one reference movement diagram being associated with at leastone reference movement of the at least one mobile device relative to theinteracting surface of the host device; and a second determining step ofdetermining that said form of the actual movement corresponds (1303) tosaid at least one reference movement and triggering (1304) a command ofthe host device according to said at least one reference movement,wherein said current position comprises: a distance between the at leastone mobile device and said interacting surface, a coordinate of the atleast one mobile device in a frame of reference associated with saidinteracting surface, and an orientation of the at least one mobiledevice according to an axis orthogonal to said interacting surface. 2.The method according to claim 1, further comprising steps of:displaying, on a screen of the at least one mobile device, at least onecontextual item for selecting said command, said at least one contextualitem being displayed at a position on the screen representing thecurrent position of said at least one mobile device relative to saidinteracting surface, selecting said at least one contextual itemaccording to a first identification of a first one of said at least onereference movement, and said triggering of said command is according toa second identification of a second one of said at least one referencemovement.
 3. The method according to claim 2, wherein said interactingsurface is superposed on said screen.
 4. The method according to claim2, wherein said screen is situated away from said host device.
 5. Themethod according to claim 1, wherein: a change in the current positionof said at least one mobile device comprises a fast variation in adistance between the at least one mobile device and the interactingsurface, and said at least one reference movement is a click.
 6. Themethod according to claim 5, wherein said command comprises activationof a selected action.
 7. The method according to claim 1, wherein: achange in the current position of said at least one mobile devicecomprises a succession of fast variations in a distance between the atleast one mobile device and a reference position in a frame of referenceassociated with said interacting surface, and said at least onereference movement is a shake.
 8. The method according to claim 7,wherein said command comprises cancellation of an action in course. 9.The method according to claim 1, wherein: a change in the currentposition of said at least one mobile device comprises a slow rectilinearmovement of the at least one mobile device relative to said interactingsurface, and said at least one reference movement is a slide.
 10. Themethod according to claim 9, wherein said command comprises a variationof a slider according to movement of the at least one mobile device. 11.The method according to claim 1, wherein: a change in the currentposition of said at least one mobile device comprises a rotation thereofrelative to an axis orthogonal to said interacting surface, and said atleast one reference movement is a rotation of the at least one mobiledevice between a first direction and a second direction.
 12. The methodaccording to claim 11, wherein said command comprises selecting acontextual item displayed on a screen and situated in said seconddirection.
 13. The method according to claim 1, further comprising:prior to said first determining step, a further step of the host devicereceiving an activation signal generated by the at least one mobiledevice further to an actuation of a user interface on the at least onemobile device to activate the first determining step of determining(1300) the current position of the at least one mobile device.
 14. Anon-transitory computer storage medium having stored thereon a computerprogram comprising instructions loadable and executable on a processorof the host device that, upon execution by the processor of the hostdevice, causes the host device to implement the method according toclaim
 1. 15. A host device (105, 500), comprising: at least oneinteracting surface (502) that interacts with at least one mobile device(501, 505); at least one electrical circuit (115); a position historyfile, said position history file comprising a set of positions includingone or more previous positions of said at least one mobile device over asliding temporal window, said position history file being stored in amemory device; at least one reference movement diagram, said at leastone reference movement diagram being associated with at least onereference movement of the at least one mobile device relative to the atleast one interacting surface; and a processing unit (255) that controlsthe host device, the processing unit configured to carry out thefollowing: a first determining step of determining (1300) a currentposition of said at least one mobile device relative to the at least oneinteracting surface by at least one inductor magnetic field inducing atleast one electrical signal in the at least one electrical circuit(115), saving (1301) said current position in the position history file,comparing (1302) a form of an actual movement of said at least onemobile device relative to the at least one interacting surface,determined by utilizing said current position and at least one of saidprevious positions of said set of previous positions from said positionhistory file, with said at least one reference movement diagram, and asecond determining step of determining that said form of the actualmovement corresponds (1303) to said at least one reference movement andtriggering (1304) a command of the host device according to said atleast one reference movement, wherein said current position comprises: adistance between the at least one mobile device and said interactingsurface, a coordinate of the at least one mobile device in a frame ofreference associated with said interacting surface, and an orientationof the at least one mobile device according to an axis orthogonal tosaid interacting surface.
 16. A system comprising the host deviceaccording to claim 15 and a mobile device (501, 505), wherein the mobiledevice (501, 505) comprises at least one location module for generatingthe at least one inductor magnetic field configured to induce the atleast one electrical signal in the at least one electrical circuit (115)of the host device.
 17. A system comprising the host device according toclaim 15 and a mobile device (501, 505), wherein the mobile devicecomprises: i) at least one location module that generates the at leastone inductor magnetic field configured to induce the at least oneelectrical signal in the at least one electrical circuit (115) of thehost device, and ii) a user interface configured to trigger sending, bythe at least one mobile device, of a command signal to the host device.18. A mobile device (501, 505) in combination with a host device, wherethe host device has at least one electrical circuit (115) and aninteracting surface, the mobile device comprising: at least one locationmodule to generate an inductor magnetic field configured to induce anelectrical signal in at the least one electrical circuit (115) of thehost device; and a user interface configured to trigger sending, by themobile device, of a command signal to the host device, wherein: the hostdevice is configured to determine (1300) a current position of saidmobile device relative to the interacting surface by the inductormagnetic field of the mobile device inducing the electrical signal inthe at least one electrical circuit (115); the host device is configuredto save (1301) said current position in a position history file, saidposition history file comprising a set of positions including one ormore previous positions of said mobile device over a sliding temporalwindow, said position history file being stored in a memory device, thehost device is configured to compare (1302) a form of an actual movementof said mobile device relative to the interacting surface determinedutilizing said current position and at least one of said previouspositions of said set of previous positions from said position historyfile with at least one reference movement diagram, said at least onereference movement diagram being associated with at least one referencemovement of the mobile device relative to the interacting surface of thehost device, and the host device is configured to determine that saidform of the actual movement corresponds (1303) to said at least onereference movement and triggering (1304) a command of the host deviceaccording to said at least one reference movement, said current positioncomprising: a distance between the at least one mobile device and saidinteracting surface, a coordinate of the at least one mobile device in aframe of reference associated with said interacting surface, and anorientation of the at least one mobile device according to an axisorthogonal to said interacting surface.
 19. The mobile device accordingto claim 18, wherein said command signal is a signal that activates thehost device to determine the current position of the mobile devicerelative to the interacting surface of the host device.
 20. The mobiledevice according to claim 18, wherein said command signal is a signalrepresenting a current position of the user interface.
 21. The mobiledevice according to claim 18, further comprising: a first locationmodule installed in a main body of the mobile device; and a secondlocation module installed in a secondary body of the mobile device,wherein the secondary body is adapted to move relative to the main body.